IceCold Posted June 23, 2015 Report Share Posted June 23, 2015 While sitting at a light, my irritating ses light came on, now what! I ran the codes and p0420 came up. After researching the code it came to the catalytic converter, fuel mixtures and air out of whack. I have noticed lately I've been burning an awful lot of fuel, however, my indicator says I'm getting 17.3 in the city, but my pocket says different. All 3 O2 sensors are new oem brand and no codes exist for such fault in my system. I did noticed that the air pump in the front on the left behind the bumper seems to be falling apart (Brittle) may need to be changed. Could this be a concern that could cause this code? I seem to have a funky exhaust smell from time to time and maybe that's a warning sign that lead to this code. Any help would be appreciated! Link to comment Share on other sites More sharing options...
Logan Posted June 25, 2015 Report Share Posted June 25, 2015 Were the O2 sensors Bosch? Logan Diagnostic LLC www.airbagcrash.com www.logandieselusa.com www.ledfix.com www.ledfix.com/yukontaillightrepair.html www.ledfix.com/ledreplacements.html www.ledfix.com/j42385toolrental.html Link to comment Share on other sites More sharing options...
winterset Posted June 25, 2015 Report Share Posted June 25, 2015 When the car is open loop, the secondary air injection pump supplies the cat with a burst of fresh air that lites up the cat. If the downstream (after cat) o2 sensor does not detect a change in the downstrean o2 sensor waveform when the air pump is running, it trips a trouble code. I have heard of some different variations of the p0420 coming on even in closed loop due to a faulty air pump. Unfortunately, a partially plugged up cat can cause a p0420, and it can also force exhaust gases back thru the second air injection plumbing if there is enough pressure - and that can be the funky exhaust smell. It can also start melting it as well. Link to comment Share on other sites More sharing options...
IceCold Posted June 25, 2015 Author Report Share Posted June 25, 2015 Were the O2 sensors Bosch? Yes, and I know what's next! Link to comment Share on other sites More sharing options...
Logan Posted June 25, 2015 Report Share Posted June 25, 2015 If you installed Bosch O2 sensors...and now you have the catalyst code...my money is on the Bosch O2 sensors causing the false code. I have seen this exact problem before. Same code. Others too..... http://www.pontiacbonnevilleclub.com/forum/2000-2005-other-than-gxp/topic2544.html The Bosch simply work different enough...where it causes false catayst codes on GM. Logan Diagnostic LLC www.airbagcrash.com www.logandieselusa.com www.ledfix.com www.ledfix.com/yukontaillightrepair.html www.ledfix.com/ledreplacements.html www.ledfix.com/j42385toolrental.html Link to comment Share on other sites More sharing options...
IceCold Posted June 28, 2015 Author Report Share Posted June 28, 2015 If you installed Bosch O2 sensors...and now you have the catalyst code...my money is on the Bosch O2 sensors causing the false code. I have seen this exact problem before. Same code. Others too..... http://www.pontiacbonnevilleclub.com/forum/2000-2005-other-than-gxp/topic2544.html The Bosch simply work different enough...where it causes false catayst codes on GM. I think the secondary air injection pump needs replacing, however, I will be replacing all Bosch 02 sensors this week. I've been running premium fuel for a while, any harm in doing this? Link to comment Share on other sites More sharing options...
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