2013 Honda civic R18Z4 p0420

**demotep3** · 19th October, 2023, 06:43 PM

Good Evening,
Got stuck with one i'm not used to, wonder if anyone can give us a hand.
Long story short, partners dads civic burning oil, put a low millage replacement engine in, all is good except p0420 cat bellow efficiency.
passes emissions but obviously the cat is damaged to some degree.

I do lots of immo work but usually obd or basic bench. never had to touch the ecu flash side of things, and thought best let someone who does this a bit more often handle it, so paid someone to re-flash and they said "turned off the lambdas". obviously the fault returned, as far as i was aware there's more to it than that and the p0420 needs identifying in the flash file and removing so it just cant appear.

I'm tempted to purchase a PCM-Flash kit and read it myself but I wouldn't know where to begin looking to remove that fault code. Would anyone on here be able to assist or have a flash file for that engine with that fault code removed, ready to write in?
Yes i'm trying to do this on the cheap, usually not how I like to do things, but ended up roped into family stuff....

Also open to recommendations to tools for the job if there is a better alternative.