PO 420 help
PO 420 help I drive a 2002 t/a m6 and she has right under 45k. I was driving home from work and suddenly I noticed the t/a didnt have any get up anymore. It is especially noticeable in 1st gear. There is almost a slight grinding sound and 1st gear at 4k im only going 30mph. I did a PCM read and got the code PO420 which I read can be multiple things. The air filter looked good so it cant be that. What else should I check out? I personally think that its the cats just based on the performance/sound of the car. If someone with some more knowledge could help me out here it would be greatly appreciated! Thanks
Best thing to do it check exhaust back pressure. If you dont have that tool, then I suggest taking it to a GM dealer. There is special policy coverage on converters for these cars up to 10 years or 120,000 miles after it was placed in service. Hell it still may be within the 8yr/80k emissions warranty. Either way, it will be 100% free to you IF the converter is diagnosed as the actual problem. 99% of P0420 codes is a failed LH converter. If you take it to the dealer, have them refer to special policy #05513. This is all assuming your converters are OEM.
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From: Ricerville
^
Probably the cat. My car has been throwing that same code for a while. I replaced the rear driver-side O2 sensor (PITA) hoping that would fix it. No luck
. I guess I need to take a trip to Summit and get a Magnaflow bolt-in and replace it.
Probably the cat. My car has been throwing that same code for a while. I replaced the rear driver-side O2 sensor (PITA) hoping that would fix it. No luck
. I guess I need to take a trip to Summit and get a Magnaflow bolt-in and replace it. Best thing to do it check exhaust back pressure. If you dont have that tool, then I suggest taking it to a GM dealer. There is special policy coverage on converters for these cars up to 10 years or 120,000 miles after it was placed in service. Hell it still may be within the 8yr/80k emissions warranty. Either way, it will be 100% free to you IF the converter is diagnosed as the actual problem. 99% of P0420 codes is a failed LH converter. If you take it to the dealer, have them refer to special policy #05513. This is all assuming your converters are OEM.
This is the one I was looking at getting. Got good reviews on adding overall power and even some mpg. May end up getting one anyway.
Well I just made an appointment today. I don't think the guy even knew about the special policy. Initially he insisted on it having to be less than 8 years old. Thanks much joshp14. You hopefully saved me that cash for other mods!
Last edited by beyonddisturbed; Feb 26, 2010 at 04:30 PM.
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From: Ricerville
That's what I should do as well, but I just don't have time right now with school. I commute to and from college, so I need that car. That's why I am planning to do it myself so I don't have to leave it for 2 or 3 days at a dealer. 
Yes I commute to and from college as well. Fortunately I do have a vehicle I have been driving during bad weather this winter. You really think it will take them that long? I had a little more faith in GM Goodwrench. O well I guess we shall see.
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I doubt they will have the converter in stock so they will diagnose it the first day, order the parts, then install the next day.
It could be a faulty o2 sensor but like I said 99% of vehicles with P0420 have been converters...and thats a lot of vehicles. Plus, GM knows there is a problem and issued a special policy on them....its the converter.
It could be a faulty o2 sensor but like I said 99% of vehicles with P0420 have been converters...and thats a lot of vehicles. Plus, GM knows there is a problem and issued a special policy on them....its the converter.
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