I JUST SPENT $2k ELIMINATING WARNING LIGHTS!!!

I recently replaced both upper oxygen sensors and this weekend drove from Jacksonville to St Augustine to Statesboro GA. 10 miles from home I get a CEL. Just pulled codes and only got P0420 - Catalyst below efficiency threshold, Bank 1.

Im assuming the old post-cat sensors are PART of the problem, but they arent throwing a code, I have a damaged exhaust heat shield toward the front/middle but its still there, just bent and torn. Car is totally stock with 155k miles.

aaannnnd GO.

 

P0420 is generally related to a faulty rear warm-up catalytic converter (bank 1 is near the firewall), not the sensors.

The V6 has three catalytic converters:
• The front warm up three way catalytic converter (WU-TWC) that’s bolted to the front cylinder head
• The rear WU-TWC that’s bolted to the rear cylinder head
• The under-floor TWC that’s downstream and mounted to exhaust pipe A

 

good info to know thanks. I read there is a way to clean the cats. Is this true or snake oil? Any chance the damaged heat shield on the 3rd cat is in play here? I would rather upgrade if I am forced to replace, what products can you suggest?

 

https://honda-tech.com/honda-accord-...erter-3234926/



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