Thread: Pontiac GP 08 - P0300 & P0420

Figured it was the cats as well, took it to a place called Iowa Muffler and Brake in Des Moines, they have always been straight with me (or so I think). He said the cats could be bad, but recommended fixing the misfire first, they recommended a small shop in the area, initially they thought it was a coil and stuck in a coil they knew was good, no go. They then determined it was the ICM that was bad, paid for the diag and headed to NAPA and picked up a new ICM, took a few minutes to install, fired it up and it instantly stalled, tried to start again it cranked longer than usual then fired up. Took it for a test drive and she drove great, neither P0300 or P0420 reappeared, I wouldn't be surprised if the P0420 reappeared.

Question for you guys, how often do the ICMs fail? The original failed and Pontiac replaced $1000, then it failed again, local shop replaced it $600, now it failed again. This one cost me $220, the top of the line one that NAPA had Delphi.

Thanks,
John

Plugs were not original, maybe 30k on them.