lonelyhighs

Just installed new headers and downpipe. Used the old 02 sensors but new gasket and bolts. Now I keep getting the P0420 CEL. Any ideas on how to go about fixing this or do I need to somehow program my ECU to cancel out that error.

It Wasn't Me

o2 simulator.

Install one. (downstream, post header)


Edit:

An old search result, to give you an idea of what I'm talking about: https://honda-tech.com/honda-civic-2...lator-1615775/

NDNV

Or search on "spark plug anti-fouler". This has worked for me.

lonelyhighs

Alright i looked them up and ordered one. Thanks guys!