P0420 again!
07-31-2009, 11:22 AM
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P0420 again! I had the dealership replace my driver's side cat last year after I got the P0420 code. It's showing up again, about a year later. I switched the rear o2 sensors to make sure it wasn't a bad sensor, and it came back with the same side. I am planning on having the dealership replace my cat again, but I am a bit worried my car has killed two cats on the same side in a year or so. Should I be looking for a cause?
07-31-2009, 01:13 PM
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I would be looking for a cause. My cats are both still orignal and my car has 113k on it. Does your check engine light flash? Also what dealership did the work? They have an 8yr 80k warranty from most gm dealers. You could also just rip them off and get the codes tuned out. Even if you do rip them off I would look for a cause.
08-03-2009, 01:53 PM
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Yeah, our emissions checks here are pretty strict I think I need to keep them on. Tuning them out might get me by, but I do want to know what is causing them to go bad. It isn't throwing any other codes so I am not sure what the problem could be... running rich would kill both sides, and it isn't noticeably burning oil. The car only has 49K on it.
