code p0420?
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Can't say for sure, but I believe that code comes up with a non standard Cat is used. There are others that would know more about that then me. That'* not a problem with my year. I seem to remember something about 00+ being funny about cats.
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You can replace the cat, or cut it off and gain 5-10 WHP but then your car is not street legal and install a 02 simulator for $42 and never see the check engine light on again for cat issues!! ![Very Happy](https://www.gmforum.com/gm/images/smilies/biggrin.gif)
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I just got this same code not a week ago! Looking into it more i found that the government requires GM to hold an 8 year 80K mile warranty on the entire pollution control system. Take it into the dealership if you HAVE NOT changed your pcm to intense'* pcm and have them replace it under warranty. Luckly i still had my old computer to swap in there before i took mine in. Also are you noticing that your boost gauge is running higher then it usually does? Mine was semi-restricted when i took it in. It would run at about 3 PSI of boost just to stay up at 65 MPH on the interstate.
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If i tell you, then i have to charge you!!
Just kidding... Here is the link on how to buy one... Rear O2 Emulator: 3800 Performance <---------------- Click here
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I had the same code and it WAS the cat. I have 73k miles on my Bonne and The cat Was covered under Warrenty. As a matter of fact... The Dealership replaced the ENTIRE Exhaust from Cat to Tips because in 02 it'* a one piece system.
) Cost me $0.00 If u had to purchase the same exhaust NEW from GM it'* almost $1,000.00
Good Luck
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