Check engine on the WRX
#1
Registered Member
Thread Starter
Join Date: Oct 2006
Location: Portsmouth
Posts: 5,772
Likes: 0
Received 0 Likes
on
0 Posts
Check engine on the WRX
I was coming back from class on the interstate (664) when i decided to fuck with some of my turbo timers features. It has a 40-whatever timer to time your pulls from 40 so i decided to go from 40-120. I hit about 115 and *boop*..on the comes the check engine light. I scan it and it read (sorry for spelling) "catalyst effeciancy below threshold" and since the cat is brand new im pretty sure the O2 went out on it. Its a 02 WRX and i JUST installed a invidia turbo back with the catted downpipe and it ran fine for about a week with multiple test pulls to check for leaks, then this happens.
Is this a common problem with other suby owners? Or other people in general? Will the bad O2 fuck up the cat or make the car run shitty (ie. rich or lean)?
Is this a common problem with other suby owners? Or other people in general? Will the bad O2 fuck up the cat or make the car run shitty (ie. rich or lean)?
#4
Registered Member
Join Date: May 2003
Location: Up on Leemor's bed...
Posts: 6,775
Likes: 0
Received 0 Likes
on
0 Posts
Re: Check engine on the WRX
It's the rear O2 sensor. The cat in the downpipe is not as efficient (therefore not as restrictive) as the stock one. So the rear O2 sensor is triggering the code.
The front O2 sensor is before the cat in the uppipe, so that wouldn't be causing it unless something is wrong with the engine.
The front O2 sensor is before the cat in the uppipe, so that wouldn't be causing it unless something is wrong with the engine.
#5
Racetracks
Join Date: Nov 2002
Location: How long is a piece of string?
Posts: 15,668
Likes: 0
Received 0 Likes
on
0 Posts
Re: Check engine on the WRX
Agreed, you're getting an out-of-range value from the rear O2 most likely. There are various (usually a little ghetto) fixes for this, look around the nasioc forum and you'll probably find a few. Aftermarket cats are rather different from stock, and the ECU is tuned for the stock cat. You could always get rid of the rear O2 and put a bypass in place of it..
#8
Fanboi
Join Date: Jun 2003
Location: Virginia Beach
Posts: 24,919
Likes: 0
Received 0 Likes
on
0 Posts
Re: Check engine on the WRX
Same thing that happens in the LSX world. After putting on my Kooks headers w/ high-flow cats etc I'd get a CEL once every few weeks for catalytic converter inefficiency. The cat is flowing more and the rear o2 picks that up and doesn't like it.
The rear o2 simply monitors that the front one is working etc so when I got my car tuned the rear o2s are simply turned off in the PCM.
The rear o2 simply monitors that the front one is working etc so when I got my car tuned the rear o2s are simply turned off in the PCM.
#9
Registered Member
Thread Starter
Join Date: Oct 2006
Location: Portsmouth
Posts: 5,772
Likes: 0
Received 0 Likes
on
0 Posts
Re: Check engine on the WRX
Same thing that happens in the LSX world. After putting on my Kooks headers w/ high-flow cats etc I'd get a CEL once every few weeks for catalytic converter inefficiency. The cat is flowing more and the rear o2 picks that up and doesn't like it.
The rear o2 simply monitors that the front one is working etc so when I got my car tuned the rear o2s are simply turned off in the PCM.
The rear o2 simply monitors that the front one is working etc so when I got my car tuned the rear o2s are simply turned off in the PCM.
Edit: Also im goin for an ECU reflash once the uppipe is installed. Will that fix the lights?
Last edited by Muncher; 06-11-2007 at 09:43 AM.
#10
Racetracks
Join Date: Nov 2002
Location: How long is a piece of string?
Posts: 15,668
Likes: 0
Received 0 Likes
on
0 Posts
Re: Check engine on the WRX
Depending on the reflash software, you may be able to fix the lights, yes. The front O2 sensor isn't going to like the lack of cat in the uppipe, so it may be responsible for the code also. Talk to whoever will be doing your tuning and see what options are available.