Funny, they didnt include the 1st 02 sensor in ghe generic data for the obdII data, which is very suprising to me. Only the second one shows up on my diagnostic tool, which reads the generic data. In any case, during a fairly normal drive I got some log data yesterday. The 2nd 02 sensor scales almost its full range during normal driving, which kind of shoots down the "simple" possible fix I had On some cars, both sensors are 0-1v sensors. For example, on my saturn, the first sensor reads nearly full scale back and forth, while the second stays within about 30mV of 500mV. So if that was our case I would say to try simply applying about a .5V signal in its place. Then see if the ECU was smart enough to know that was not normal.

On ours though, my bet is that the ECU is smart enough to know that the second one is not reading correctly, because its readings arent changing over time.

I plan on getting the Toyota specific data for my scan tool. If I do I will look at it again.. or I will if I get a header soon.

 

The one from ClubsciontC is the correct one and is drilled out, I've had mine on for over a year and 10k miles and no cel. If the code your throwing is the P0420 code then it shouldn't have anything to do with your MPG.

 

Well at my dealer told me my sensor was broken, but maybe they got that code because of the headers.... i get 220 Mpg every tank flooring it alot... i need it fixed if im loosing hp.

 

From what I understand the P0420 code is for a "malfuctioning Cat" Letting you know that you need to get it fixed. I don't see how or why the ECU would richen or retard timing, since the catyaltic convertor has nothing to do with fuel mixture or timing.

 

yeah, use two......that is what i did.

 

watching....woulb be nice if you could do the "simple fix"....possibly use a +.5V source from the car itself, and send that to the ECU...

does the O2 have one or two wires....if it's two, could it possibly be a variable resistor? that would make sense as to how much voltage it readds....just oopens and closes with the exhaust gases....if so, couldn't one replace it with a smalle potentiometer to reduce the voltage output returned to the engine?

i sure hope so.....but if i am wrong, alas, on to a more expensive fix

 

so im just getting a little light? but what if my sensor is brokenlike they said??

 

Maybe lay off if it a little. I know that sounds dumb but give it a try on a tank and see what it will do.

My understanding of the function of the downstream (after cat) 02 sensor in an OBD car was to monitor catalytic converter efficiency. The upstream like engifineer said should sweep from .3vdc to about .7vdc after the engine has reached normal operating temperature and switched to closed loop operation because the exhaust gases have not travelled through the cat yet. The downstream will remain flatter with less fluctuation due to the catalytic converter doing it's job.

That's what I remember from engine performance (efi) class and here's what I found online. Once again, YMMV.
http://www.aa1car.com/library/ic50234.htm

JOe

 

Also, which o2 sensor eliminator are you using?

 

anti-fouler from clubsciontc.com

 

anti-fouler from clubsciontc.com i try not flooring it but i live in miami andi get tryed so much.. it like impossible for me..

 

so let them try you and wave them off

 

anyone have any more ideas?

 

ive had my cel on for about 12 k miles since i got my aw header i installed the antifolers still cel.. dealer ship told me a while back my sensor was broken.. i thought mayb they said that cuz they didnt understand i was missing a cat .

well 2 days ago i got my bodykit installed i leave the shop with the cel on and about 60 miles later it just turns off. and sudenly i get about 60 miles more to
the tank with same the same kinda driving style~


and i checked my cel led since i changed them to blue to c if it was the ledt hat went out but no..

what just happend?

 

good Questions

its hard to tell...

 

same thing happened to me, after 3 months of driving my CEL randomly went off. as far as my gas mileage, i think it got worse with my CEL off, but i've got nothing to prove it.

the thing that confuses me though is when the CEL is on, the car is supposed to be in "limp mode". but my car pulled harder noticeably harder with the CEL ON. can anyone explain why this might be happening? or is has this happened to anyone else

 

limp in mode will limit your transmission an normally not allow you to run past 2nd gear or a certain rpm depending on what type of transmission you have, o2 sensor so far that i have heard, has not caused a car to go into limp in mode.

 

limp in mode is really just a seafety featur to protect what ever components that are left from serious catastrophic damage, while still allowing you to get to the closest available shop. Your o2 sensor monitors your exhaust gases and will let your computer know if the fuel trim is running too rich or lean or just right. if it is running too rich or too lean it usually meants that something id being overcompensated for and getting too much fuel or too little fuel.

 

If you have the antifoulers and are still throwing a cel here is a good (FREE if you still have the stock exhaust manifold) fix.
1. Knock the catalyst out of the manifold. It will come out in big chunks.
2. Take your two antifoulers apart.
3. Cut a piece of catalyst to fit in the antifouler. Be careful not to make it to thick or you will smash it when you screw the two antifoulers together.
4. Install back into car.
5. Reset check engine light.
6. No more cel.
**This modification is only necessary if you already have the antifoulers installed and are throwing a cel**

I have had to do this in a couple of different vehicles where the antifoulers did not work. I have yet to have any cels after doing this. I can not guarantee that it will work for everyone else but for the cost it is worth a try.

 

clubsciontc.com is a site w/ a good antifouler price and product?