GSXRAntwon Posted January 2, 2013 Report Share Posted January 2, 2013 Just bought an 08 Silverado 2500 and it keeps throwing a P0420 code. I've replaced the left rear O2 sensor, no luck. Can anyone help me? Quote Link to comment Share on other sites More sharing options...
Cordell Posted January 2, 2013 Report Share Posted January 2, 2013 Usually a cat. Quote Link to comment Share on other sites More sharing options...
SinisterSS Posted January 2, 2013 Report Share Posted January 2, 2013 Usually a cat. Bingo Quote Link to comment Share on other sites More sharing options...
STEVE-O Posted January 2, 2013 Report Share Posted January 2, 2013 All in favor (hand raise)... Cheap fix tune it and have them take it out of the computer. Then you are runner and have no more Cel Quote Link to comment Share on other sites More sharing options...
caseyctsv Posted January 2, 2013 Report Share Posted January 2, 2013 Since it is emissions related it may still be under warranty. Worth a shot. Quote Link to comment Share on other sites More sharing options...
BIGGU Posted January 2, 2013 Report Share Posted January 2, 2013 That it just do a o2 spacer after the cat and ignore it. Quote Link to comment Share on other sites More sharing options...
Cordell Posted January 2, 2013 Report Share Posted January 2, 2013 Since it is emissions related it may still be under warranty. Worth a shot. GM covers cats 8year 80k miles, if its covered bring it in I'll take care of it. Quote Link to comment Share on other sites More sharing options...
STEVE-O Posted January 2, 2013 Report Share Posted January 2, 2013 Since it is emissions related it may still be under warranty. Worth a shot. This the thought didnt even cross my mind. Quote Link to comment Share on other sites More sharing options...
GSXRAntwon Posted January 2, 2013 Author Report Share Posted January 2, 2013 Thanks guys. It looks like the cats have been replaced before. It's an 08 with 99k on it so no emission warranty . Would u replace both cats again? I don't just want to bandaid it I want to fix it Quote Link to comment Share on other sites More sharing options...
GSXRAntwon Posted January 2, 2013 Author Report Share Posted January 2, 2013 Or shoul I just punch the cats out and put spacers in the O2s? Idc about emissions really.... Quote Link to comment Share on other sites More sharing options...
Cordell Posted January 2, 2013 Report Share Posted January 2, 2013 I'd punch them out and have Dyno Brian tune out that shit. I've heard that spacers work, but have never used them and would rather the computer not look for the sensors at all. Were they replaced with factory cats? I've seen quite a few cars and trucks come in the shop with undersized aftermarket cats causing the same issue. You may also want to make sure the enigne is operating well as poor economy can clog up the cats as well. Quote Link to comment Share on other sites More sharing options...
TurboNova Posted January 2, 2013 Report Share Posted January 2, 2013 the spacer has worked in multiple occasions that I have seen. Id really do that route first Quote Link to comment Share on other sites More sharing options...
GSXRAntwon Posted January 2, 2013 Author Report Share Posted January 2, 2013 I'd punch them out and have Dyno Brian tune out that shit. I've heard that spacers work, but have never used them and would rather the computer not look for the sensors at all. Were they replaced with factory cats? I've seen quite a few cars and trucks come in the shop with undersized aftermarket cats causing the same issue. You may also want to make sure the enigne is operating well as poor economy can clog up the cats as well. They look like aftermarket cats, they're huge so I think they're suited for the engine size. I think I'll try the spark plug non foulers drilled out trick, then if that doesn't work, punch em out and go get a tune from Brian. Brian told me he doesn't have the software for 08+ trucks (Gen 4) with VVT. Quote Link to comment Share on other sites More sharing options...
Brandon Posted January 2, 2013 Report Share Posted January 2, 2013 They look like aftermarket cats, they're huge so I think they're suited for the engine size. I think I'll try the spark plug non foulers drilled out trick, then if that doesn't work, punch em out and go get a tune from Brian. Brian told me he doesn't have the software for 08+ trucks (Gen 4) with VVT. Hp tuners "should" support it, so more then likely it is just credits you would need to purchase. Quote Link to comment Share on other sites More sharing options...
Cordell Posted January 2, 2013 Report Share Posted January 2, 2013 They look like aftermarket cats, they're huge so I think they're suited for the engine size. I think I'll try the spark plug non foulers drilled out trick, then if that doesn't work, punch em out and go get a tune from Brian. Brian told me he doesn't have the software for 08+ trucks (Gen 4) with VVT. It all has to do with how much catalyst is inside them, cheap ones even though oversized still may not function as the vehicle was designed. A lot goes into catalyst design so the after market cat likely isn't even "bad" it just isn't correct for the truck. Quote Link to comment Share on other sites More sharing options...
GSXRAntwon Posted January 2, 2013 Author Report Share Posted January 2, 2013 Ok thanks. Quote Link to comment Share on other sites More sharing options...
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