I'm doing this because there isn't a specific writeup, and we get WAY TOO MANY CEL FIX threads. Now, it should be even more easily searchable.

The purpose of this little mod is to fix the Check Engine Light caused by the installation of aftermarket headers. Aftermarket S-pipes will not cause this light to come on. There are several other fixes available commercially, but many of us aren't willing to pay $50 when this $3 fix works just as well, if not better.

I've had the megan header on for about 10 days now, and travelled over 300 miles. No CEL whatsoever. Gas mileage has not been affected, as far as I can tell. (I got 290 miles on a full tank, but have been flooring it excessivley to feel the new header)



Here's what you'll need-

1-Aftermarket headers installed on vehicle.
2- HELP brand spark plug antifoulers, 18mm, part number 42002. ($2.99 at most auto parts stores. I got mine at autozone.) You'll need one pack, which contains 2 antifoulers.
3- Drill with 1/2 bit able to cut metal. I used one designed for wood, and it worked fine.
4- Jackstands to lift vehicle, and tools (I used a wrench) to remove second o2 sensor.
5- Penetrating spray lubricant to help with sensor removal.

How-to

1- Raise the vehicle and secure it with jackstands or other methods of your choosing. I do not recommend using just jacks.

2- Locate the S-pipe, immediatley after the header. Locate the secondary O2 sensor sticking out of the S-pipe, which will be more towards the passenger side and slightly behind the horozontal plane of the axle.

3- Unplug the other end of the sensor, so that the wire isn't damaged in the removal. You'll see where it attaches, and its a simple clip. Use your tools and lubricating spray to pull the secondary o2 sensor out. THIS SENSOR IS CROSS-THREADED, you will be damaging the threads in removing it. Work it very slowly out, take your time, and limit the damage to the threads as much as possible. You'll want something left on there to keep your sensor in.

4- Take your drill with the 1/2inch bit and one of your antifoulers. Drill straight through this antifouler, widening the hole at the end and turning the antifouler into a straight little metal tube. This will take a while, and get quite hot in the process.

5- Screw your modified antifouler into the un-modified antifouler. Notice that you've created a little "chamber" for your O2 sensor, with a little hole at the end. This little hole will be exposed to the exhaust stream, and limit the amount of gas that the sensor sees.

6- Screw the sensor into the modified antifouler. Screw the whole assembly into the O2 sensor bung. It will look like this.

O2sensor > Modded Fouler > Unmodded fouler > O2 sensor hole.

7- Clear your CEL by either disconnecting battery or OBD-II tool, whichever you prefer. Be sure you plugged the sensor wire back into the electrical connection.



And enjoy your now CEL-free car!


If you still have a CEL after this-

1-Check your work, be sure you didn't install it incorrectly.
2- Be sure its the second sensor, NOT THE FIRST ONE THAT SCREWS INTO THE HEADER. The first sensor acts more as an A/F meter, and will throw off your power and gas mileage.
3- Be sure you didn't damage the sensor. This is common, and easy to do since the sensor is difficult and cross-threaded.

If all of this doesn't work, then you'll need to try something else. This solution will work over 95% of the time, and has been used for years in a number of different cars.

Yep.. the anti-foulers have a price tag because a lot of people dont have access to the tools to do it themselves.. but those that can.. this writeup is great

Good writeup.... Nice to have something so people don't need to pay 50 bucks for a lower priced fix.

I'm sorry to disagree with the 95% thing but its more like 65-75%. Mine feel within the numbers that don't work. It might be b/c I have cai with s-pipe and a header so the flow is a lot more than that of a header alone. I am not sure but I used my laptop to datalog and the anti-fouler will not work with i/h/spipe setup! Sorry to say but this is true. If you want a good fix relocate the second o2 sensor on the midpipe behind the cat there and you will have no issues with aftermarket headers. I am using zpi midpipe and Magnaflow cat and resonator. The cat I bought is a 2.5" in and out carb cetified california emissions and has a o2 bung in it already. I will not have anymore cel problems b/c of the aftermarket header one I get these parts. I am just waiting on the midpipe with should have shipped so it will be complete soon.

If what you say is correct, then the problem will be addressed later.


This does not detract from the usefulness of this fix. If it doesn't work, then you've lost $3. Big whup.

Let's try to keep things positive. This is working for me, is working for others, and will work for many people. I didn't spend 30 minutes typing that up to start arguments about its effectiveness.

I didn't say that to start a argument. I just stating what I have found to be true. How many miles have you put on your car since? Do you drive interstates a lot and get past 80mph? I have notice if you keep it in the city the cel tends to stay off but once you get it on the interstate and have at least 200-300 miles on the car the cel pops.

I have upwards of 4000 miles on my anti fouler with no CEL. Ive had K&N CAI, stock airbox, Injen SRI, Injen CAI, stock s-pipe and CC s-pipe and have not had a CEL since the day I installed my header and anti fouler at the same time. Ive done city driving, Vegas road trips, open track racing and everything in between with no problems at all. I am proof that the anti-fouler mod CAN work perfectly even though others cant get it to work no matter what they do.

About 300+ miles, including a 50 min highway/interstate trip to the track, racing at the track, and 50 min back.

There's probably another factor involved that's causing yours to pop. What it is, I have no idea.

^ I agree as well.... I have thousands of miles CEL free with my antifouler after not having success with O2 Sims....

And my engine has all kinds of fun modifications... and does all kinds of things....

I really think there is another factor where people have antifouler failure...

What header do you have to start with and what midpipe do you have. I belive and aftermarket header and zpi s-pipe flows really well causing the cel. I have the Alphawerks header and it tested the highest gains. Also the s-pipes 02 bung location might throw it off also. I am aware that the s-pipe alone will not cause a cel, its caused by the aftermarket header not having a cat.

It's not going to matter which header you work with.

The ZPI S-pipe would work even better with the antifouler mod, due to the relocated sensor.

I'm sorry it didn't work for you, but this doesn't mean it won't work for the average joe who's looking to try quick fixes before dropping 15x more cash for yet another error-prone method.

The system compares the readings between the O2 sensors both before and after the Cat. If there is no difference, or not enough, then the Cat is either not there (in the case of a header) or not working. The antifouler trick moves the second 02 out of the stream a bit, thus causing a difference in reading. If you look at the $50 fix thats out there, it is simply an exaggerated version of the anitfouler. It is longer to move the 02 further out of the stream. I am not sure if there is room, but if you did the antifouler trick correctly and it did not work, maybe try three of them.

The ecu actually has specific voltages that it looks for in the sensor. Its not really comparing the two. It is making sure the voltages are within set parameters and if doens't then the cel will set.

Is it possible people who are getting CELs with antifoulers are having too little flow being picked up by the second O2 which is causing the ECU to beleive the pre-cat is clogged?

Just a thought...

mods need to sticky this please!!!!

Lots of people are looking for a good explanation

Sorry to say this but the too little flow is wrong! I have a laptop and datalogging capablility. I used this to log with and actually if you were getting little exhaust that wouldn't be a problem. The problem is getting too much emissions and causing the cel! I know this from datalogging a stock tc and one with aftermarket exhaust system!

I was just offering that as something to look into that may have been previously overlooked. What are the parameters the ECU needs to see in order to not throw a CEL? Is there a high and low value that triggers the CEL?

I believe that may be the case with the antifouler mod and individuals still getting a cel....

that the antifouler takes it too far out of the flow for that setup and it trips the CEL as a result.... there has got to be a fine line of where the sensor needs to be placed... I'm pretty sure those still getting a cel are on the too little flow side of it, than getting too MUCH flow with that setup.

But, who really knows..... I'd just play with it both ways until I got it to work.... at the price of an antifouler, you can make three or four different setups, before equaling the price of the other mods on the market.

I was just offering that as something to look into that may have been previously overlooked. What are the parameters the ECU needs to see in order to not throw a CEL? Is there a high and low value that triggers the CEL?

Yes there is a high and low value. I don't know exactly the value but if its lower than .015 it will set the code. And yes my problem was caused by too much flow. The anti fouler would work if you keep the rpm below 3500 when you hit 4000 the voltage spikes and over a period of 40-500 miles it will trip it. Don't get me wrong the antifouler trick may work for you its a hit and miss thing. It will either work or not work.

Sorry to say this but the too little flow is wrong! I have a laptop and datalogging capablility. I used this to log with and actually if you were getting little exhaust that wouldn't be a problem. The problem is getting too much emissions and causing the cel! I know this from datalogging a stock tc and one with aftermarket exhaust system!

No one said it was 100% flow.. by moving it out of the flow you are reducing the amount it "sees" resulting in a lower reading in the second sensor. It doesnt just look at the threshold reading on the second sensor either. By having that, plus the values from the first sensor, you can tell if the CAT is doing its job. At least this is how I have seen it work on other vehicles.

The best setup (and the only one I would pay $50 or more for) would be a simple simulator. All it takes is a little bit of time to figure out the relationships between the 02 sensor readings and the normal operating voltages. You then develop the simulator circuit to read one sensor and apply the correct signal to the second one to simulate what the system expects to see. Maybe I should make this a future project along with the others I have :P But, I am pretty sure they have some decent ones out there, I just never looked for them.

I know that! I am a automotive technician and have been for 7 years. I have tried simulators several different kinds. The best luck I have had was the Zpi sim and it still didn't work. Zpi worked with me on it and we could not come up to a logical reason why. The problem is there is a voltage spike in the 02 sensor at 4000rpm. Even on a stock tc the voltage spike shows a little just not high enough to set the cel. If you want a permanent fix go to a exhaust shop and get a o2 bung welded in behind the cat on the midpipe and relocate the o2 sensor and you won't ever have a cel from the aftermarket header.

yes, there has to be another factor. i still have my CEL after the anti-fouler mod. i've checked my work twice and even got a couple of friends to do the same. still we cant find anything wrong. somethings jacked up.

and how do u get 290 miles on a full tank? even if your gunnin it sometimes. wow!

yes, there has to be another factor. i still have my CEL after the anti-fouler mod. i've checked my work twice and even got a couple of friends to do the same. still we cant find anything wrong. somethings jacked up.

and how do u get 290 miles on a full tank? even if your gunnin it sometimes. wow!

I have gotten below that regularly with normal in town driving. My max is 380 and my min is about 250. You have to realize that a "tank" isnt the same for all.. some fill up lower that others. Considering I almost always have a 12 gallon refill, thats from 20 to 31 mpg... almost exactly what the tC is rated for.

I was very much enjoying my new mod :)


Mods, please sticky or please consider a DIY section. I'm going to put together a quick "taking out the backseats for dummies" as well, and probably my own version of GFI.

If you are lazy and want to find the "HELP" defouler online, I found it as a brand called Motormite, with the same part numbers. I have another question though, is the connector on the rear o2 harness a generic square 4 wire plug? I am planning on buying an extension harness from summit racing and then relocating the rear o2 sensor behind the cat on the draxas exhaust. That wasy I shouldn't need to fool anything.

Mine anti-fouler fix works fine after over 15,000 miles

I have the DC header and K&N intake, and the anti fouler method worked until I hit somewhere between 80-95 mph on the freeway. Im going to add another unmodified antifouler to the ones I already have on there to further remove the O2 sensor from the exhaust stream and will see if this will help my problem. It will look like this.

02 sensor opening in s pipe - unmodified antifouler - unmodified anti fouler - modified anti fouler - O2 sensor .

Im hoping by adding an additional gap, there will be less air going to the sensor and I wont trip my cel.

Interesting concept. I think it should work.

hey toyota_scion_tc, You have the zpi s-pipe on your tC right? I read on the zpi s-pipe veview, that the zpi s-pipe because the o2 sensor sits back farther on pipe itself that it wouldn't be necessary to do the anti-fouler trick is this incorecct?

yeh my anti-fouler doesnt work either..i have AW header, Injen CAI, and stock everything else. i was thinkin mayb if i get an s-pipe to get more air flow then it might work..but first imma try to add another link to the anti-fouler to make it 3 instead of two. my bro said that might work

yeh my anti-fouler doesnt work either..i have AW header, Injen CAI, and stock everything else. i was thinkin mayb if i get an s-pipe to get more air flow then it might work..but first imma try to add another link to the anti-fouler to make it 3 instead of two. my bro said that might work

im doing the same thing as you, i think im going to put it on tommorrow so ill let you know if it works or not next time I hit 85-90mph which is usually where the cel light comes on.

Is there enough room down there for an extra anti-fouler? From what I remember it was a pretty tight fit when I installed mine

yeh my anti-fouler doesnt work either..i have AW header, Injen CAI, and stock everything else. i was thinkin mayb if i get an s-pipe to get more air flow then it might work..but first imma try to add another link to the anti-fouler to make it 3 instead of two. my bro said that might work

im doing the same thing as you, i think im going to put it on tommorrow so ill let you know if it works or not next time I hit 85-90mph which is usually where the cel light comes on.


well for me the CEL didnt come on until mayb 285 miles after ecu reset. i did this two times so i know its around that mileage. dunno bout you though. mayb wait til after 300 miles? keep me posted because i dont think it will show up right away. weird how urs comes on when u hit 85 mph though. that didnt happen to me..

yeh my anti-fouler doesnt work either..i have AW header, Injen CAI, and stock everything else. i was thinkin mayb if i get an s-pipe to get more air flow then it might work..but first imma try to add another link to the anti-fouler to make it 3 instead of two. my bro said that might work

im doing the same thing as you, i think im going to put it on tommorrow so ill let you know if it works or not next time I hit 85-90mph which is usually where the cel light comes on.


well for me the CEL didnt come on until mayb 285 miles after ecu reset. i did this two times so i know its around that mileage. dunno bout you though. mayb wait til after 300 miles? keep me posted because i dont think it will show up right away. weird how urs comes on when u hit 85 mph though. that didnt happen to me..

I get close to 300 miles per tank of gas, which takes me about a week to get through. So i'll be able to tell you in about a week if it comes on due to mileage.

Is there enough room down there for an extra anti-fouler? From what I remember it was a pretty tight fit when I installed mine

From what I remember, I thought there was enough room for an extra anti fouler, maybe even two? I guess I'll find out tommorrow though.

I also have the K&N CAI, DC Header and the anti fouler didnt work for me either. I am waiting on the peice from MM to try and see if that fixes it. I will let everyone know on that peice, if it works for me.

will I added an extra anti fouler, and it worked. took the car up to 95mph and the cel light didnt come on. The only problem is that I think it is rattling against some other metel piece when I accelerate, because I hear a little tapping noise that I didnt use to hear before. I will fix this however by just padding the antifoulers so that if they hit something, it wont make a tapping sound.

One question - will the cel light affect gas mileages? Thanks

hey toyota_scion_tc, You have the zpi s-pipe on your tC right? I read on the zpi s-pipe veview, that the zpi s-pipe because the o2 sensor sits back farther on pipe itself that it wouldn't be necessary to do the anti-fouler trick is this incorecct?
That is incorrect b/c the oxygen sensor is still in the exhaust stream and getting the same flow from it.

I got my ZPI Midpipe in its bolted on with the Magnaflow 12646 resonator. Sounds really great. I have the factory header on still. I am waiting to get my 2.5" Stainless steel flanges for the Magnaflow 43036 cat I am going to put in. I am flanging it incase I have any problems with this cat or go turbo later and decide to remove it. I have a complete 2.5" stainless exhaust on my car now it sounds great. My sound shouldn't change too much when I put the alphawerks header back on b/c I will be adding in the catalyic converter on the midpipe.

I was planning on getting the zpi s-pipe later next month and when i read that you didnt need to do the anti-fouler trick I was stoked. Oh well, thanx for the info though!

hey sensei , still no CEL ?

thanks for the write up im gonna try this in two weeks when i get my megan header thanks wish me luck

does it go off with the injen cai and a dc header, just ordered my header today. do i need to do this

does it go off with the injen cai and a dc header, just ordered my header today. do i need to do this

So does it still hold true that I won't need to use an antifouler for the Megan S-pipe that I'm getting here in a couple of days? I ordered that along with a Megan header. Should I be good without an antifouler?

i have the megan header stock s pipe and ingen CAI and it went off ill be doing this mod today to fix the cel

i did the fix yesterday the 13th reset my ECU with a friends little CPU that connects to the port by the lever to open your hood, got on the freeway this morning cruising at about 85 for 5 min. no check engine came on thanks

what is this $50 fix that everyone keeps talking about? i just installed megan headers and a zpi 2.5 inch mid-pipe and i got 2 things wrong.
1) CEL keeps coming on
2) it is so flippen loud i got one ticket already and have been pulled over like 3 tims after that. sucks. what should i do about the noise?

what is this $50 fix that everyone keeps talking about? i just installed megan headers and a zpi 2.5 inch mid-pipe and i got 2 things wrong.
1) CEL keeps coming on
2) it is so flippen loud i got one ticket already and have been pulled over like 3 tims after that. sucks. what should i do about the noise?

i bought a silencer for my ehxaust that should help and dont gas it to much
I have a megan header and a tsudo mid pipe and cat the only thing i dont have it the S pipe, i did the anti fouler fix and so far no problems

hey well i got the trd axle back. do they make one for it and if tey do where can i get one?

measure the diameter of the tip is should be 3 1/2 or 4 1/2 and you can find one at any performance shop they might have to oreder it thow good luck

How can I know if my O2 sensor is bad or good? I took a reading of the CEL and it gave me excessive emission, which makes me assume that the second O2 sensor is working... right?

yup the o2 is working if it wasnt there would be an o2 code

when i get a header i plan on welding in a cat right after the s-pipe and moving the 02 sensor just so i dont have to ____ with it anymore

yup the o2 is working if it wasnt there would be an o2 code

when i get a header i plan on welding in a cat right after the s-pipe and moving the 02 sensor just so i dont have to ____ with it anymore. also it would help with the rasp from the header

yup the o2 is working if it wasnt there would be an o2 code

when i get a header i plan on welding in a cat right after the s-pipe and moving the 02 sensor just so i dont have to flip with it anymore. also it would help with the rasp from the header

I reset the CEL to see if it will turn on again. It's been about 130 miles so far an no CEL. Last time it last 'till 185, so let's see...

As for moving the O2 sensor to a location after the s-pipe, talk to someone who understand better than I do, but I heard that moving the sensor to a further away location can give you a CEL for some other reason. I also heard that if you move them closer to each other (to the one on the header), it may eliminate the CEL. Again, these are things that I heard from a mechanich friend of mine. I'm clueless about it (if I knew I didn't have the CEL, lol).

Good luck

ive tried all of these things everyone has mentioned and no success so far. what would you do if you have tried all the antifouler tricks with no luck.....would you reinstall the factory header or stick with side affects of the cell? is the header worth that much when it comes to the cell? i would relocate the sensor after the secondary cat but not forsure how to do so. and has anyone tried the piece of catalyst between the antifoulers?

I read somwhere about puting a small piece of catalyst from your stock cat inside the antifouler. Not quite sure if it works or not, but im open to ideas because im also having this problem. Just tired of reseting my ecu every 1000 miles or so.

I had to reset mine again at 170. This weekend I will try to remove the antifouler and reinstal. If still doesn't work, I'll try to drill a very small hole on the side of the fouler so that the gas can mix with pure O2. Hopefully this will trick the O2 sensor. I'll post any results here.

DC Sports header with 3 non foulers, half inch hole in one and no problems yet. I will keep you up to date.

Here is what someone else tried... I'll try this too

let us know how it turns out

pimptc

I reset my CEL this week for the third time. It's been a little over 200 miles and the CEL haven't come on yet. If it comes on this weekend, I'll do something and post an update.

I'm still waiting for the CEL to come on... :tap: is it possible that the ECU "learned" that it is OK not to have the first catalic converter?!? It's been about 350 miles and nothing yet. :relief: The first and second time with the antifouler the light came on at 180 and then 170 miles.

so whats the news? any success?

^^^ The third time the cel came on was at 480 miles, but the antifouler was lose. I was going to drill small hole in one of them, but after thinking about it I realsed that water can get in through the hole and burt the O2 sensor.

Now I added the 3rd antifouler to see if this will work. So far I have about 150 miles with no light. I'll keep you updated.

thanks

Update: 300 miles and no CEL on 3 anti-fouler

when you say 3 anti fouler....do you mean 3 packages totaling to 6 small peices put togther or just 3 pieces put togther?

^ 3 pieces alltogether. After installed, you should see:
O2 sensor on the drilled antifouler on a second antifouler (no drill) on a third antifouler (just like the 2nd) on the pipe.
||===-

By the way, I'm getting to 500 miles with no CEL (opposed to the 480 record with 2 antifoulers)

awesome, i will try

megan peeps = 3 foulers? that sucks

^^ I guess that the flow of the Megan header must be higher than the DC Sports.

Update: 580 miles and no CEL (3 foulers)

i got alphawerks and im using 2

DC people are using 2 as well... only the megan people are having that problem... I think it is the -$400 effect... hehehe... at least it is working with 3 (so far)

so hows it comin? still cel free?

I never posted again after I got my custom exhaust. I have had it on a little over a year now I believe. I haven't had any cel since I put at least 20,000 on it. Not a one! If you want a permanent fix listen to what I said before. I can go boost just like I am now and never have to worry about the secondary o2 sensor throwing a cel unless it goes bad!

so hows it comin? still cel free?

850 miles and counting! No CEL with 3 antifoulers...

so for all you seasoned mechanics out there, im an electrical guy who dosnt know much more than highschool classes about engines. Im looking to run either a Fujita CAI, GReddy DT-Exhaust, Megan Racing Header..... or, a Injen CAI, DC 4-2-1 Header, Borla Exhaust... two questions, any suggestions on which will be better, and two, there seems to be a contreversy on if this mod works to fix the light, which setup would have a higher chance of the fix working?

you prolly have better chances with dc sports, btw it's not 4-2-1 header, the only true 4-2-1 header is MMW

Any option with the antifouler trick, you will be fine. By the way, close to 1,000 and no CEL.

now is this only for the tc or is this for the xb as well

i used the mmw cel elimminator wit dc headers n invidia spipe and no cel ... the mmw cel elimminator WORKS!!!

now is this only for the tc or is this for the xb as well

Good question... I think I saw somehere that this works for the xB, but I'm not sure though.

^^ haha xb? now will that give it triple digit hp to the wheel???

ok, quick question, as far as relocating the sensor behind the secondary cat (which involves cutting the wires) would extending the wires mess up the signal the sensor sends to the computer sense it is further away?

^^^Now you got me... someone else with mere experience, please help!!!

I don't think that even the dealership will knwo the answer for this one

Finally installed my Megan header yesterday. Put in the standard two antifoulers on the OEM s-pipe and no CEL as of 24 hours. Will update at around 500 miles.

Quick tip: 7/8 wrench to remove it. If you can, try and find a six-point box wrench instead of a 12-point. 15/16 will strip your bolt. Seriously.

anyone know about the sensor distance problem? Really a big factor before i decide to do this. Being that i have to put a new bung in my pipe and close up the other one.

hows the no cel and mileage going?

^^ Hey bro, I lost count.... I must be close to the 1500 with no cel. I'll check it tomorrow and let you know

(3 antifoulers)

awesome, hope it works for me! if not relocation here we come......just hope i dont have to go back to stock header just to get rid of this very annoying cel.

^^ I say "do it!" Try with 2 antifoulers. If it does not work, add the third one. I doubt that both options will fail, but if so, you still can use a O2 simulator. Good luck

I just put in my Megan S-Pipe today (M&D Racing Garage FTW! :lol: ), and I went ahead and kept my two antifoulers on to be safe. Since installing the Megan header on Sunday, I've only driven about 220 miles, so I still have yet to update after about 500 miles on the CEL. No CEL yet! *knocks on wood*

...should I keep the antifoulers on my aftermarket downpipe, or should I pop them off?

i had the alphawerks header on my car w/ supercharger and then a 2.5" s pipe>30" resonator>stock mid>trd axleback...I threw the code the first couple hundred miles of having the header on and then once I got my supercharger installed and ecu reflashed it never threw the code ever again...that was without the use of any antifouler or o2 simulator...I guess I was just one of the lucky ones that never had a problem

I just put in my Megan S-Pipe today (M&D Racing Garage FTW! :lol: ), and I went ahead and kept my two antifoulers on to be safe. Since installing the Megan header on Sunday, I've only driven about 220 miles, so I still have yet to update after about 500 miles on the CEL. No CEL yet! *knocks on wood*

...should I keep the antifoulers on my aftermarket downpipe, or should I pop them off?


leave the foulers or you'll get a CEL, theres no drawback by leaving it on anyway

Update on 3 foulers: 3,500 miles and no cel (damn, I'm driving a lot more than I thought!)

You can use this for the invidea s-pipe

http://www.scionlife.com/forums/viewtopic.php?t=175210

how can you tell if your either of your sensors are properly working without doing the burning trick i heard about? Every time i reset the cel or modify the antifoulers with all the ways listed to fix the cel, the light alwayse comes back on consistently around 9 miles give or take.

Take to a mechanich to have the code read. If the code is for emission, that means that you are not doing the tricks right. If there is a problem with the O2 sensor itself, the code should acuse the O2 sensor.

ok AutoTube.net has a anti-fouler o2 sensor simulator that they say works, any one have it on Megan Headers and down pipe cuz im about to buy the 2 and wanna make sure i dont have a problem with the cell and hoping that this will work

over the weekend i installed my megan headers with the anti fouler and it worked for about 30 miles. I disconnected the ground off the battery to reset and it never came back on. The people having problems, have you disconnected the battery? Today i installed dc headers that i wanted instead and the trick still stuck. its a quick fix for the much needed headers. "just untill the turbo comes around"

I saw someone on SL that was making an anti-fouler with a 90degree bend in it. That one seemed to work better, but I can't find who that was any more. Anyone know?

Well, I forgot to check in after 500 miles. It's been a little over 1000 now and after a Megan S-Pipe at 300, I'm happy to say that I haven't had one CEL yet. Yay!

I saw someone on SL that was making an anti-fouler with a 90degree bend in it. That one seemed to work better, but I can't find who that was any more. Anyone know?

http://www.scionlife.com/forums/viewtopic.php?t=175210

cel back on, damn! I think im going to add a 3rd anti fouler

Thanks for the link, volcom.
Which one are you using?

which one am i using? You mean the cel fix? Im using the quick anti fouler trick on this forum. One completely drilled and one un modified put to gether and installed on the down pipe with the 02 sensor attached to it.

I'm using the antifouler (I did the trick before the fix was posted) with 3 pieces and it's working fine for me, no prbolems at all.

I have the megan header. v1. it has a pre cat :) axle back draxas. cel came on after 25 miles.I got up to 90mph then when I got off the freeway and was going 35mph cel came on. ugh! I'm gonna try to do this mod on sunday.

51 miles later and cel came back on this morning!

^^^ Do you have 3 foulers?

no I don't sorry. I should have stated that I don't have any. my question was why does the cel come on really quick?

there is no room for 2 antifoulers. it will rub against a piece of the steering thing

^^^ Take to a mechanich to have the codes read. If it only gives you "emissions", 3 antifoulers should do the job. With no fouler, I could drive no more than 15 miles without CEL. With 2 antifoulers, the furtherst I got was close to 500 miles, I think, but usually CEL went on at 150 miles.

technically wouldnt a hi-flow cat work?

^^^ Well, you would have to find a way to put that cat between the two O2 sensors. Even then, you may not have the problems solved since the reading on the second sensor will still be higher than normal.

i mean on the midpipe so that it wouldnt have too much oxygen going through the 2nd 02 sensor

it would be sucking the air from the 2nd o2 sensor

im just curious, is the primary cat made into the header and the secondary cat the same type of cat? if so could you just relocate the o2 sensor behind the secondary cat, i know it requires cutting and welding in a new hole, but ive tried every way to get the cell gone and NOTHING works and my inspection is up. im despirate

pipmtc, go buy the mmw cel eliminator.. I guarantee that it works. who else agrees? I got mine from a dealer $49.xx don't remember exact proce except that it was 49 and like 6 bucks for shipping where as mmw wanted 10bucks for shipping. its deff worth the money

honestly i dont think ill buy another thing, im tired of buying everything anyone tells me works.....now im leaning toward my sensor is broken...yeah...im on a random hunt for the magical cell fix, what ever it may be

Have you gotten yoru code read to see exaclty what CEL it's throwing? It may not even be the one that the antifouler fixes. p0420, I think it is?

I got two foulers on and I got a CEL twice already. I gotta go back to AutoZone and clear my CEL and get another pack of the anti-fouler so i can add another fouler to my existing two foulers. Hopefully that'll get rid of my CEL for good.

BTW, whats so bad about driving with the CEL on anyways?

Oh, last time I got my CEL scanned, I got two codes. I remember one of them was p0420. I'll write it down tomorrow when I get it scanned again.

DTC P0420 Catalyst System Low Efficiency

What does that mean?^^^

DTC P0420 Catalyst System Low Efficiency

What does that mean?^^^

I'm guessing it means your primary catalytic converter isn't working too well... seeing as it has been removed. :P The MMW CEL fix may be a better solution in your case.

that 420 code is the one the anti fouler trick fixes. It means your cat (which has now been removed) isn't working well. The anti fouler pulls the sensor out a bit so it will sense less of the increased air flow, and then read correctly. But your CEL will stay on with whatever other code yoru gettting, and that anti fouler may not fix that.
The bad thing about running with a CeL on is that you will not pass an emmisions test.

heading to autozone now...will try to get the other code and buy another anti-fouler so i can add another fouler to my two foulers.

quick question will my cel come on if i just swap the spipe cuz dats all i really wanna do everythin else is still stock

Does the fact that a system is turbocharged change the parameters of this fix? I would think so see as how it is a similar catless system, but the flow rates are higher.... any suggestions?... cause I'm going to try this fix

2 boosted guys here have the fix. One worked, one didn't.
And yes, the s-pipe will make a difference because that is where the second 02 sensor is.

So, you guys who are boosted and have gotten Tunes...

You got the tune with your CEL on?

I'm the only tuned one untill this weekend.
we cleared the CEL before tuning. tuning wasn't great and CEL came back on after a couple days.
I tried 2 different maps that don't fight the ECU as much and my CEL never came on with those.
It mostley has to do with tuning, but it may partially be due to how the 02 bung is situated for a particular turbo kit.

quick question will my cel come on if i just swap the spipe cuz dats all i really wanna do everythin else is still stock

95% sure that it wont only b/c the light comes on when the Primary cat is removed...such in the case of putting on an aftermarket header. When you do that, its not that the second O2 sensor is getting too much flow, its that its reading too many pollutants, since the cat isnt there. So these antifoulers just pull the O2 sensor out of the air flow so that it can't "see" any pollutants. Hope this helps.

that makes sense, but didn't you get the anti-fouler fix designed specifically for a certain s-pipe? why would it need one if it did not throw a cel?

Or is it cause by changing the header thew a CEL but changing to a certain s-pipe made the other anti foulers not fit?

that makes sense, but didn't you get the anti-fouler fix designed specifically for a certain s-pipe? why would it need one if it did not throw a cel?

Or is it cause by changing the header thew a CEL but changing to a certain s-pipe made the other anti foulers not fit?

I did have to get a different designed one b/c I got the Invidia s-pipe and you supposedly cant do this version of the antifouler mod with it b/c of where the bung is the foulers and O2 sensor hit like a support bar or something like that. I also need the antifouler thing because I installed the header the same day so I did header and s-pipe with the other mod and never got a CEL.

so if someone didnt care about the price to fix this problem what else could be bought other than the anti foulers? i installed my invidia s-pipe and started getting a cell(off and on).

so if someone didnt care about the price to fix this problem what else could be bought other than the anti foulers? i installed my invidia s-pipe and started getting a cell(off and on).

http://memimage.cardomain.net/member_images/6/web/678000-678999/678488_179_full.jpg

http://www.scionlife.com/forums/viewtopic.php?t=175210&highlight=invidia+cel

the first thing you have to remember is to go down to autozone and have them read your code for free. The anti fouler only fixes one code, and just cause you put the s-pipe on does not mean you got the code that the anti fouler fixes.

Hmm....Well what ever 02 Code is throwing...If it doesnt put it in limp mode, you can still get it tuned...

ne one has a picture where or how to drill the anti fouler?

http://www.scionlife.com/tech/images/header_install_tc/29.jpg

1/2 inch drill bit

thank u soooo much!straight down right?

yes, straight down to one of the antifouler,
what header are u getting? i got DC header, after 7k miles. no problem so far.

I am currently using this fix on my Alphawerks/Invidia install

I have NO CEL after 500 miles

Kudos on the inexpensive fix!

hi everyone, i got the megan headers, got cel after bout 40 miles, (got it on the highway) going ~60mph. anyways i got the antifoulers, but cant get the damn O2 sensor off, its WD-40'd, when i first went at it i turned it about 1 full turn and it became loose but wouldnt come off, and turning it more in either direction makes it tight as hell again... how do i get this cross threaded thing out!?

i have seen a lot people complaining about the O2 sensor are cross threaded. IT IS NOT CROSS THREADED. Just take your time and it will come out.
I would tighten it first and slowly loosen it again.

Still no CEL from my 3 foulers...

Mine lit up ~600 miles after the anti-fouler (x2) install and then magically disappeared after another 60 or so miles. Another ~1000 miles and it has yet to return.

Will the car still run rich with the antifouler trick?

Will the car still run rich with the antifouler trick?

? The car really isnt running rich unless you have a turbo/super charger that isnt tuned properly. This O2 CEL isnt coming on b/c its running rich, its coming on b/c the main cat is gone so its not breaking down the unspent fuel from the motor...making it seem like its running rich when in fact it's still running the same, just making more pollution which trips this O2 sensor.

great explenation, amd!
:clap:

I know.... I know.. what can I say :P :rofl:

Got my materials and I'm tying this fix on tomorrow.... and I am Boosted :P ... so I will post my findings :eyebrow:

just did this mod and want to know if the CEL will shut off on its own without resetting the ecu. makes sense it would go out if the readings are within the OK range and the ecu 'thinks everything is ok' again. ( i just feel it would be more satisfying to see the light go out! instead of waiting for it to come back on... :tap:. )

It should.

bump

will someone please help me? I cant get my f@&*ing CEL to go away and stay away.

I have an 08 and I am runninng the DC sports header.

I've tried 2 non-foulers and 3 non-foulers and multiple ECU resets.

Does anyone of know something I can try?

...works wonders

http://www.scionlife.com/forums/viewtopic.php?t=175210&highlight=

Good on ya! I've been looking for that damn link, amd!
Should have know you would have it!

hey batman, did you check to see what codes you have?

:bow: thank you amdforever

and Mr_Meaty, I did scan it 2 CELs ago. I cant remember the numerical code but it was something like emissions defficiency.

Good on ya! I've been looking for that damn link, amd!
Should have know you would have it!

hey batman, did you check to see what codes you have?

:rofl: Yeah, I think I'm that guys spokes person since no one has ever had a problem with it. Wish I could have grabbed mine off of the the tC before the trade in....

:bow: thank you amdforever

and Mr_Meaty, I did scan it 2 CELs ago. I cant remember the numerical code but it was something like emissions defficiency.

No problem man, I just hope he is still making them for people! I recommend him to everyone that does a header install. It works on all S-pipes and you can set it to where you want it positioned, just remember to tighten down the nut on it like a mofo if not it'll come loose.

:bow: thank you amdforever

and Mr_Meaty, I did scan it 2 CELs ago. I cant remember the numerical code but it was something like emissions defficiency.

No problem man, I just hope he is still making them for people! I recommend him to everyone that does a header install. It works on all S-pipes and you can set it to where you want it positioned, just remember to tighten down the nut on it like a mofo if not it'll come loose.

Yeah he said I can buy one for $25. I probably will, I just hope this works. I can't imagine why the non-fouler trick isnt working since i have the DC headers. Maybe the 08 has a more sensitive O2 sensor

it should its worked for everyone so far, so you'd be the first :D

nice write up, saving it in "my post"

AARGHGHHHH by mistake i bought the 42004 instead of 42002... it wont work, do they?


btw there is two ring in the pack.. do i need to use them???

1) ok.. i got the 42002... they dont have any kind of ring whatsoever... so.. i got two piece.. and i tried to drill it with a brand new drill.. i could drill it all the way to the end.. but i couldnt go more then 80%!!!!!!!!!!!
i dont know.. maybe the drill wasnt sharp enough... i tried to start from the other side.. i coulg drill a little bit but not too much.. today i went to the shop.. the guys said buy that $12 dollar bit.. thats one of the best.. ok... i came home.. tried both side.. NOTHING HAPPENED!!!!!!!!!!!!!!! WH@!$A F#@$K??????????????????????????????? i cant drill it thru!!!!!!!!!!!!!!! the brand new 12 dollars drill bit didnt do anything with that antifouler!!!!!!!!!!!!!!!! what?? that last 20% part made by kriptonit? OR WHAT??? IM GOING CRAZY!!!!!!!!!!!!!!!!!! i almost throw away my drill machine.................. i think im just gonna put it on like this.. if a brand new drill bit doesnt do anything.. then i dont know..

i thinkgin to return that drill bit.. because this is pathetic



update: ok i got it.. it was hard.. i saw some sparks aroung the drill bit:D:D:D:D

anyway... i installed it.. reset the ecu.. the windows not working the the IDLE is HORRIBLE!!! below 500 rpms

for the windows, look in the manual, it tells you how to reset them. for the bad idle, look back over your install and make sure BOTH O2 sensors are plugged in. and make sure your maf sensor is plugged in too.

http://www2.djn-ice.com/CSOCSO-SUPRA/scion/howto/IMG_2136copy.jpg

after this i realized i have to turn it to the other way................

The care will idle rough after an ecu reset. I have seen it idle that way for about 50 miles after it before. Just give it time. Take it out, drive it using various speeds, stop and go and cruising and it will gets itself back on track

Hint for next time: Use a wrench :)

And not to ask the dumb question, but did you have the drill in forward the first time you tried it ? :)

When I first added my anti-fouler I had about 50-60K miles, at the time I had Megan header, ZPI s-pipe and Injen cold air intake, now I have about 93K miles with the addition of a Agency power crank pulley and 2.5" custom header back exhaust system and still CEL free.

Oh...and i drive my car hard everyday.....

ok.. i was doing like 90mph.. and the cel came back.... BUT!!!! i just realized : the first owner of the car wanted to get rid of the cel... so he did the same thing on the headers o2 sensor.. lol... anyway.. im gonna uninstall the fouler from the header's o2 sensor and install the 3rd fouler on the 2nd o2 sensor.... yaaay i dont have to buy anything because i have it already...

btw isint bad if i had that thing on the first o2 sensor???

DAMN!!! today the car almost fell on my chest!!! i was under my car putting on the third piece of the fouler and i tightened the foulers and the car started to lean away.. and of course the car fell on the ground right on my little lamp ( crushed it............) i was fast so i made it out before the car fellt on the ground... but it was close!!!!!!!!!!!!!!!!!

Please say you had it on jackstands and they broke...if not its your own fault man.

it was my own fault.. i didnt pull the e brake and it was on the included stand from the trunk.............. it was scary.........

btw my car is okay...

it was my own fault.. i didnt pull the e brake and it was on the included stand from the trunk.............. it was scary.........

btw my car is okay...

Well...glad to hear you are ok as well....next time leave the car in gear as well.

it was in gear..... but my car lowered.. im a big guy and i had to jack up the car so much only the rear left and front left tire was touching the ground.....

invest in some jack stands. seriously.

Good writeup

hey so how deep do u have to drill the antifouler exactly? thanks a ahead of time

Got a set of DC Sport headers yesterday and user the Antifouler Trick. Got about 50 miles on them so far and no CEL. Thanks for the write up

hey so how deep do u have to drill the antifouler exactly? thanks a ahead of time
i drilled all the way thru

like even passed the tiny hole?

yes... i said.. all the way thru... both ends had big holes.

sav thnx man

Just an update, since I haven't been here in so long...

3 antifoulers + Megan header = no CEL for about 30K miles

cool!!! i have the same setup:D

just to update, I still cant get rid of the CEL. I've tried 2 non-foulders, 3 non-foulers and the L shaped CEL fix that amdforever recommended, all to no avail. Im open to anyideas. Some ideas of mine include putting a hole in the last (ie closest to the pipe) non-fouler so that atmostpheric air will also enter the simulator and show less O2. Or perhaps a small piece of catalyist between nonfouler 3 and nonfouler 2 would clean any fumes before reaching the 02 sensor to also give a clean reading.
I would appreciate any ideas, thanks in advance. Who knows maybe this emissions CEL is just incurable for 08s...

wait...did you go to autozone and have them read your codes? What codes are you throwing?

then you have different problem.........................

wait...did you go to autozone and have them read your codes? What codes are you throwing?

When the CEL came back with 2 non-foulers I scanned the code and it was for emmissions, I havent read it since then, but since it comes and goes I assume its emmissions. If i keep my engine under 4k, the code stays away for a while but if I rev higher than that, the voltage spike never fails to make that annoying yellow light come back. I will go to autozone this weekend and double check just for good measure.

The fault code you prevent with the antifouler is P0420, "Catalyst system efficiency below threshold".

http://www.scionlife.com/tech/manual/?manual=tc05_0382

If your code is not P0420 then you've got a different problem.

i've had mine on my turbo car for almost 2000 miles now and the light has yet to show its ugly face again.

hey, I plan on installing my megan racing headers and megan s-pipe this saturday and i from what i've read so far it said megan headers need 3 anti-foulers would that be on the 2nd o2 sensor? which is near the s-pipe? what about the 1st o2 sensor on the header? do i put nothing on that one? and also if its just on the 2nd o2 sensor what are the orders again? is it o2 sensor -> drilled anti-fouler -> regular anti-fouler -> regular anti-fouler> and the end of the o2 sensor thing? sorry im in need of help haha thanks!

1) do not touch the firs o2 sensor ( on the header)

2) you have to you 3 fouler on the second o2 sensor

3) about the orders: you need the dril it because the o2 sensor wont fit/srew in.. so..

s pipe< regular<regular< drilled fouler+o2 sensor

wow how many ppl here use 3 foulers? i opnly used 2 i drilled and one regular and i have a megan 4-1 header and never in all my 10-15k miles have not got a CEL

Sorry I havent been online to answer questions.

I had the aftermarket header for about 3 months, then traded back to stock to conform to STS classifications for autocross. I then took about a 1-year hiatus to get my ____ together for medical school.

I'm glad to see people have been answering my questions in my absence.

Been through the surprisingly rough winter up here in Washington state with the Megan header and downpipe. and two antifoulers on the downpipe. Installed it towards the beginning of last summer and I still have yet to throw a CEL. I'm sure it probably wasn't necessary with a newer downpipe, but I did it anyway. No CELs over here.

ok so i have megan racing headers / megan s-pipe with 2 antifoulers / stock mid pipe and i drove like 200+ miles for the past week and no CEL came up. but when i went to a exhaust shop to get them to cut my stock mid pipe both the round things on the stock mid pipe the big round one (resonator) and the small round one which is the cat? and i added my 27 in magnaflow resonator.. but after like 30 miles today my CEL came up... anyone know whats up?

is it because i have no CAT any more? since i removed the header cat and the mid pipe cat? or is it cause of the s-pipe with only 2 defoulers? should i put a 3rd defouler in?

ok so i have megan racing headers / megan s-pipe with 2 antifoulers / stock mid pipe and i drove like 200+ miles for the past week and no CEL came up. but when i went to a exhaust shop to get them to cut my stock mid pipe both the round things on the stock mid pipe the big round one (resonator) and the small round one which is the cat? and i added my 27 in magnaflow resonator.. but after like 30 miles today my CEL came up... anyone know whats up?

is it because i have no CAT any more? since i removed the header cat and the mid pipe cat? or is it cause of the s-pipe with only 2 defoulers? should i put a 3rd defouler in?
i belive the only imptant cat is the one on the headers. i would try 3 and see what happens. you never know :P

oh ok so i should put on a 3rd and unplug the battery and put it back after a min or 2 right?

yes

oh ok. i hope theres no problem with my CEL or anything for not having any cat at all on my car....

hey im putting headers on in a few days i was wondering if most people needed one two or three Foulers, and if you use more then one do you use both the moded and un moded Fouler and put then together and place that on top of the original one or do you only add another moded Fouler and make the chamber bigger?

for me , i bougth a pair of those antifouler. They come in 2.
I drilled a hole in one of them.
The O2 sensor goes into the drilled one,
Then the drilled antifouler goes into the undrill one.
The undrilled antifouler goes to s-pipe.
http://i11.photobucket.com/albums/a156/gammatnt/car%20stuff2/o2sensor.jpg

did one set take care of it? cause i have one set and its drilled already i just haven't installed it yet, if im going to need more i would wanna do it before i put the stuff on the car

yes, i just used 1 set, i have a DC header by the way.
I have heard Megan header are sort of hit or miss.

if u have megan header probably u will need 3 of those..

get two set anyway.. its cheeeeeap...

Thanks for the write-up wasn't sure if I needed to drill all the way through or just past the first part. A 1/2" bit looked too big to use but it worked perfectly. Thanks again!

just installed the DME header and antifouler into s-pipe ... and guess what, it doesn't work :tap: CEL still there ... sigh

how did you install it? how many foulers, did you reset the battery?

Yeah how many foulers......me and a buddy are installing his an about a week and he has two anti foulers.......if it does not work I am gonna hvae him get the Weapon R and do it.........as it works........but spendy for a little L pipe tube.....

I have tried simulators several different kinds. The best luck I have had was the Zpi sim and it still didn't work. Zpi worked with me on it and we could not come up to a logical reason why. The problem is there is a voltage spike in the 02 sensor at 4000rpm. Even on a stock tc the voltage spike shows a little just not high enough to set the cel. If you want a permanent fix go to a exhaust shop and get a o2 bung welded in behind the cat on the midpipe and relocate the o2 sensor and you won't ever have a cel from the aftermarket header.

Over a year and 25K no CEL.

I got the custom angled antifouler from InLikeFlint ....

Installed it same time as header and I haven't thrown cell yet .....

i got 3 antifoulers and no cel since last year...

with two foulers the cel came back on the highway.

for the people who is using more then 1 fouler

are u running stock exhaust.??

im running strup header.
it comes with 1 fouler.
when i installed it i had tanabe exahust on .


when i took off the tanabe and went back to stock

my CEL came back.
and seems like it wont go away.


aa by the wayy for the poeple using 2 or 3 anti foulers

did u guy have to erase the code after installign the foulers? to get rid of CEL?

or did the CEL just dissapear after installing it?
or did it dissapear after driving for couple miles??

you always have to reset.......

hmm is it normal that
after getting the cel
maybe like 1 or 2 days later the CEL dissapears
and then couple hundreds miles later the CEL comes back?

i've heard of a few people with that issue...I think you need to add another antifouler on there...inconsistency...

The trick to the antifouler is torun your car for about 15 minutes at idle. Don't rev the engine just let the computer get used to the new setup.

it might come back on the highway.... if it does then you need a third antifouler...

my CEL came back after 1000 miles and couldnt figure out why. When i put it up in the air the s pipe somehow started to unbolt but even since then its worked great. Thanks

So here is something along the same lines, but might be slightly different.

I have the Tusdo header and Mid-pipe going into the Dezod exhaust system. The car was running really rough and dying and the dealership said it is going into a safe mode because of the o2 sensors.

My mechanic, who is a good friend, told me to looking into a O2 simulator. However I am seeing a lot of talk about using the Anti-fowlers. My two questions are:

1) Which one is the best to use?

2) Where do I get said one?

I stopped coming to tC land on this site about a year ago because of fellow tC owners, it looks like the douches have left and people can post questions with out being flamed. Please do not let me down in this.

Kirby

To clarify, does it continue to run poorly after a while? If you disconnected the battery for a while during install, it is perfectly normal for the car to run like crap for a bit. Drive it around for a while and the ECU will re-calibrate and it will smooth back out. I seriously doubt what your dealer told you. The second O2 has nothing to do with how the car runs. It is there solely to monitor the performance of the pre-cat in the header. When you run a header without the cat, it simply sets a code that means the precat is not doing its job. The AFR's are still taken from the primary O2. So as long as it is in tact, then the car will run fine. The anti-fouler is used simply to supress the code so the light wont be on all the time (so you will know if another code arises).

So:

1) If the light is on, check the codes and see which ones are set. If it is just the cat efficiency code then your car should run fine.

2) If you have not driven it much since you disconnected the battery, drive around for about 30 minutes or so (shutting off the car and restarting during that should help) and see if the idle comes back to normal.

If there are other codes set, tell us what they are and we can help diagnose them

This site is still filled with self-proclaimed know it all douche bag kids that know little more than to bolt on a part and call themselves a tuner, thus spouting out horrible misinformation. There are definitely less of them than there used to be though. I nearly stopped coming here altogether, but still know some cool people here. I still tend to go to other forums more though, since a lot of the more experienced people went there.

So the header has been on the vehicle for about a week and it is my Daily Driver. What is happening is when ever I stop the vehicle will sputter out and die.

I am not throwing a CEL, but the scanner at the dealership shows the ECU in a failsafe mode. When they started investigating it, they said, because of the header and the mid pipe, the O2 sensors were reading two drastically different numbers at idle and the engine shuts down to protect itself.

This is where my question about an o2 simulator comes in handy. My friend, who works at the dealership, said that he should be able to wire the front and rear sensor together on a simulator to read the same numbers. I would just need to upgrade my wide-band A/F gauge to a more advanced version so I can watch what is happening.

My other option is, I am getting 550cc injectors installed and the vehicle dynotuned. We can use the standalone unit to make the vehicle think it is never idling. However, I am not really liking that plan.

Any thoughts or suggestions?

Well.. the primary and secondary should not read the same (that is what throws a code).. and one is used like a wideband while the other is not.. so I would not wire them together ;)

Your issue is not because of the header throwing the readings off. Like I said before, the system only cares that the cat is working.. it is not setting running parameters off the secondary reading (just telling you that the cat is not working), so they are not correct in what is causing your issue. Something else is going on.

I have my Fujita CAI, DC HEADER and Greedy Ti-c Exhaust. Was driving with Cel for the past 3 months, but its not happen anymore since yesterday. This antifouler works well... Let's see what happen in the future

Just out of curiosity, anyone here that has a 2009-up with aftermarket headers with this mod and it works? And yes I read all 12 pages. I guess it really doesn't matter what year it is. Just comfort for my brain. LOL!!!

Anyone have updates on this?

i have weapon r header/s-pipe, 2.5" exhaust, descendant manifold wit k&n filter and no cel issues. put evrything on around 18k and now have 47k on motor wit 2 trips back to az from wa state. oh and mines an 09' tc wit manual trans as well.

The anti-fouler trick should work for any ODBII vehicle, this isn't just a Scion thing. But it's always good to know what code you're throwing first, P0420 is a good indicator that this fix will work for you. If you are getting a P0130, P2196, or P2195 then it's more likely you've got a bad 02 sensor. I was throwing the P0420, sensors checked out fine and the exhaust sys was/is solid (no leaks). SO, I cleaned the MAF, put in new plugs, PCV valve, cleaned K&N filter & cleared ECU, CEL came back. So, installed the anti-foulers on sensor 2 and no CEL for the past 300 mi. CEL usually comes back within 50 mi. Currently running stock exhaust on a 2006 xB but upgrading to a header and catback in about a week. Of course the cat could be going but there's no indication that it's cherry'd from getting to hot, sulfur/egg smell, or hard starts on mine.

Awesome info, I have done this to my dc sports header and it worked like a charm and has been for 2000 miles:)

My goes on and off all the time. I going with a weapon r fix.

i try that method and it didnt work, so i got rid of the headers :(

great write up i try a different method but it didn't work, now i going to try this

If you have the Megan header some people use additional anti foulers. I kept the original 2 since there's not much room to begin with. I just added a bunch of small washers I had laying around between the non drilled and drilled foulers. The idea is to restrict the flow to the sensor. The washers give it more obstacles for the air to go through. I've never had CEL pop up since day one of install. Hope this helps.