At 21K miles, the Check Engine, VSC and TRAC OFF lights came on on my xB. My xB has the AEM cold air induction system. I bought my xB in CA 14 months ago and drive it on the highway extensively. The local dealer here in TN, where I live, said that the computer trouble codes were conflicting and only compounding the mystery, and also: "We don't really know what's wrong with it..." But, after 3 repeat visits the local dealer decided to put in a new Mass Airflow Sensor to hopefully solve the problem.
I have the AEM cold air induction system. AEM recommends cleaning the filter every 50K miles, SCION says every 30K miles. I cleaned and re-oiled the filter after the first incidence of these mysterious trouble lights. The dealer blames the AEM cold air system and tells me that I must clean and re-oil the air filter at every oil change and can expect problems caused by the AEM system in the future.

Anyone else have a high(er) mileage SCION w/the AEM cold air induction system or this mystery of a problem?

 

Edit: That was a little odd. No clue what it did that. I think this is a bad ECU problem. I recall some other ppl having a problem like this & I think thats what they said was causing it. Im not fully sure on this though :oops:

 

what a cop out
If you oil it too much the oil can ruin the MAS.

I have 20k with Injen short ram , no prob yet.

 

Personally I don't think your VSC and Trac system has to deal anything with the Mass Air Flow Sensor. Looks like a ECU problem or some sort of a wiring problem. My .02 cents

 

You know, a few months ago, the same thing happened to me. Except it was because my rear left tire was rubbing on my ABS wire (long story). And then about a month ago, the lights came back on. The dealership pretty much told me they didn't know what was happening and just restarted the car's memory.

I'm having a lot of trouble with my xb lately and i think i've been to the dealership about 5 times in the past 3 or 4 months. I'm sad.

 

actually it does! I had the same problem and the dealer found that the sensor did not have a good seal on it. So the sensor got dirty, the dealer cleaned it and now no more problems.
Little note: I didn't twist the bulb housing on my taillights properly and the VSC and Trac light came on too!! How wierd is that?!?!

 

This has nothing to do with your intake...The problem is more than likely a faulty knoc sensor...I had the problem on my box at only 3500 miles...

Tell them to check your sensors on the computer and I can bet its your knoc sensor and that intake (especially being the AEM scion brand sold to us from the dealerships) cannot be blamed as your problem...

What year is your box??? If it's an 04' there is a TSB thats going to be put out for this knoc sensor problem, but I'm not sure when...I'd heard about it at out last meeting...Apparently this sensor is failing on quite a few boxes these days...

Oh and if they try and tell you its safe to drive as it is they're wrong...Tell them to keep it and give you a rental car until they have your box fixed..."Yes"you can drive it in this condition, but if this is the problem thats found on your box the valve timing is going to be way off and you'll get horrible gas mileage...

Best of luck to you and your box,i hope you get it going soon...

DAN

 

I thought the knoc sensor was only on the boxes that were dying on the road.

 

I disagree with the comment that it is not intake related.

I had the exact same problem with my box:
https://www.scionlife.com/forums/vie...645&highlight=

and it was the MAF sensor. The codes pointed the way to the diagnosis and the knock sensor was never a consideration.

Whether oil comes from an "over-oiled" air filter or from the breather tube, it is the intake that is facilitating contamination of the MAF sensor...

The dealer told me that AEM intakes were different in such a way as to prevent MAF sensor failures, but I thought it was BS since my Injen was virtually identical in design... now it seems that AEM's are no better in that regard. :oops:

There must be some set of variables that combine to create MAF sensor failures for some CAI-equipped and not others...

My guess is that when MAF sensors are assembled, like any other mass produced product, there are production variations. Combine a sensitive MAF sensor with an owner who opts to go full CAI (regardless of brand) and they have a failure.

 

I had the same lights twice, first time it was the charcoal canister at 6k and then one time the gas cap was not on tight enough

 

charcoal canister = because u like to top off?

Jeff

 

Freaking gas cap can cause that thing to go off too?? Dam we got a sensitive system! well, I hope you got some answers from someone on this topic PushyTop :D

 

Wow guys I'm really sorry for just assuming this problem can only be caused by a faulty knock sensor...I had no idea that the system is so sensitive even the gas cap being on a little loose could set it off...

I hope you get some answers on your box too, and that it'snothing serious :D

DAN

 

my xb had the same problem .i took it to a dealer and they told me that a relay basically shorted out and they had to order the part .but problem was it took them almost a month to the day i took it in to fix it

 

yup, so whats the list so far thats connected to the VSC/TRAC

1.) MAF sensor
2.) knoc sensor
3.) tailights not conected right
4.) loose gas cap
5.) shorted out relay
6.) abs wire

Am I forgeting anything? :o

 

Add speed sensor unless you have that as abs wire.

https://www.scionlife.com/forums/vie...vsc+trac+wheel

 

what's with all the speculation?

the trac/VSC lights flash on whenever you have an ECU error code. in the scion case there are probably other things attached to it as well, as noted by stylis.

 

I think he was making a point that numerous failures can trigger the same sequence of lights...

 

Than I guess thats it, we now have the list of everything that can cause the freaking VSC/TRAC light to come on. So when ever someone searches it, the list is here. Good hunting everyone! :D

 

this has been coming up a couple times and narrow down to actual problems and not just assuming it will be either the knoc sensor or with the intake. i believe dan (7red7) had to wait for about month also for the part.