I have a 2003 Pontiac GrandAm.Code reads PO420.What is my problem?

Question

I have a 2003 Pontiac Grand Am.2.2L.4 cyl.Code reads PO420.What is my problem.

Answer 1

Hi there.

This usually means you need a new catalytic converter. In some cases the rear O2 sensor can cause this code to apper, also a rich fuel mixture can cause it as well. Most often however you need a new converter.