2007 Mercury Milan Q&A

2007 Mercury Milan Question: PO420 code

Car has 82,000 miles. Replaced battery and one month later emission light came on. Codes PO 305 and 301 cylinder misfires came up. Replaced all 6 spark plugs and 6 ignition coils and intake gasket. Cylinder 5 kept misfiring and burnt out the engine control module so replaced that also. One week later emission light came on again and now have a PO 420 code. Other than replacing catalytic converter is there anything else it could be -
Answer 1
i think you need to seek help the misfires poss burn't catt out. the po420 could be a couple of issues.like catt ,o2 senors or exh leaks -