Throwing CEL with new exhaust????

Throwing CEL with new exhaust????

So I've had my exhaust for about a year now and its starting to become a pain in the ass. Ever since I got it I've been throwing CELs for faulty O2 sensors. I've been trying to figure out why but I can't. I still have the cat installed and both O2 sensors. I didn't change the mixture or anything so why is this happening? Each time i get a CEL it codes for the upstream sensor which is the one on the header. Like I said I've replaced it many times (about 4) and about every 2 months I get a CEL. I'm so mad about this that I've been riding around with a CEL for the last month because I don't know what to do anymore. Any suggestions would help. Thanks.

sorry...but hahahaha. search function helps.


replace the o2s and cat.

I don't really see how this is funny...but thanks. I don't have time to sit around and look through every post that has the phrase "check engine light" or "exhuast problem", so that's why I started this thread. I thought that since someone else may have had this problem, I could get a response and fix my problem once and for all. If this is a problem, I'll just delete this thread and find another way to solve my problem but thanks again.

BTW, both O2 sensors and cat are new.

then check the codes its throwing and update us. its probably an o2 sensor, they can be faulty.


its funny because almost everyone who does aftermarket exhaust on a corolla throws a cel

Ok, my bad...didnt mean to have an attitude.

I got the code a while ago and I forget. I'll have to get it again.

Since the corollas are so damn hard to get rid of the CEL just do what I did. Remove the bulb just make sure you scan your car every once in a while so nothing major pops up. Before I switched gauge clusters in my car, the CEL actually burnt out bc it was on so long for a faulty cat.

I wouldn't do that... in my rolla I get shit mileage once I get a CEL..

rolla goes in a gas sipping frenzy

from the usual 185~200 I get from 9gal refills (I never let it go past 3/4 of the tank :3)
I get 150~

what do u mean by aftermarket exhauset like header, cat , muffler like that or just header and muffler or do u have stock parts

I have an obx header with stock replacement cat and 2.25 in. tubing with a magnaflow muffler. Should I replace the cat again? Cus my codes don't say anything about the cat, it says that I have a faulty sensor or that a sensor is not reading right.

have you tried putting on the stock header, clearing the code and seeing if it comes back?

I have not tried that yet, but I have thrown that idea around both because it may stop the CEL and becuase the OBX header is crap and makes annoying/raspy noises due to the cheap tubing. I just might try that.

better off starting from one end and working your way through until you narrow down the issue or putting it completely stock and seeing if the issue still comes up.

yeah the tubing blows dick, im probably gonna be replacing mine.

sounds like you have a exhaust leak judging by the noise and this would give you a CEL. I would get a flexpipe put in like the other ppl with the OBX header.