Okey i have been getting a CEL for like a month after installing my cat back system. It was bought used, so it could be the cat. The code was a P0420 i believe. Now i heard it can be either the 02 sensor, or the cat converter. Is there a way for someone to tell if the sensor is bad so i dont end up going out and buying a cat that i really dont need or what? Cause if i know the 02 sensor is bad, i'll just replace that instead of getting a whole new cat converter. Any help i'd appreciate! Thanks
Not sure...I don't understand why your cat-back system would cause that. Do you know the defenition of that code?
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Do you have any exhaust leaks?That could trip the check engine light.If you have a rubber mallet,get under the car and hit the cat.If you hear a rattling noise,your cat is shot.Or you could have a partially clogged cat.Have someone rev the motor and put your hand on the muffler to see if you have enough exhaust flow.
Peter
'06 Cobalt ss/sc W/G85 Package
Gm Stage II W/2.79" Pulley
K&N Drop In Filter
Custom Magnaflow Dual Exhaust
well ive seen from a post on here from a honda owner about the bank 2 (sensor behind cat) getting to close in the mainstream of the readings which makes the CEL come on. So there's a post on how to move it outwards, and i'm going to do that first, and if that works great, if not i'm gonna have to see if someone can check my sensor's to see if they are bad. If they are switch them, if not getting a new cat.
