× Auto Repair Pros Member Benefits TechHelp Knowledge Base Forums Resources My iATN Marketplace Chat Pricing About Us Join Industry Sponsors Video Members Only Repair Shops Auto Pro Careers Auto Pro Reviews
Join Now
International Automotive Technicians Network
Re: GM dealer says P0420 caused by downstream sensor. What say you?
Posted to Technical Discussion Forum on 3/9/2007 1 Reply

yes , but you stated the fuel trims are / were all "good" , now the dealer tech states the rear o2 is pinned lean ...

how can both statements be correct ?

a bad cat coupled with a recent failure of a rear o2 sensor can be caused by over filled oil.

what ... Login to read more.

1 Replies Received (View Replies)