Like the topic says. Is it very likely to happen immediately or would it take a while? I got a carsound 2.25" cat instaled recently and a week later I get a CEL 67. Is it the cat itself or a damaged o2 sensor? Thanks in advance.

Pete

 

sometimes, depending on which cat used, the high flow cats flow too well and won't come up to temp inorder to light off. when this happens, ECU looks at rear O2 sensor and sees its signal matching that of the primary O2 sensor even after engine is in closed loop. when it sees this, the ECU takes this signal from rear O2 and uses it to verify cat operation. if cat is not coming up to temp and rear O2 signal matches front O2 signal then it sets check engine light on because it thinks cat has lost efficiency.

Your best bet is to install rear O2 sensor signal eliminator and then should be OK

 

Yeah I lookind into one of those. My biggest concern is if Meineke damaged my o2 sensor during installation. The CEL came up twice since install, about a week apart. Is this normal too? Would what you are describing make the CEL light up every time I start the car or what? I know of a few people that have aftermarket cats that have had no CELs at all - lucky bastards.

 

you could be on to something in regards to damaged O2 sensor. You'll just have to get under car and inspect it for loose pins, damaged connectors, pinched wires, insulation rubbed through, etc.

Good luck. Let me know if you find anything.

If it is a cat issue, this it 2 trip logic in ECU and should only set code once car has ran 2 consecutive trips with same failure. Hence why lite has only come on twice in a week or 2. If it were damaged O2 sensor or harness where a something with sensor or harness was physically broken, ECU should set check engine lite pretty quickly, and would come right back on even when code was cleared. If lite comes on everytime that you start car, probably have damaged O2 sensor. If only comes on once or twice every week or two, probably cat is causing issue.

Again, I suggest O2 sensor eliminator if found that cat is causing issue.

Just my 2 cents though...