Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - Restoring old catalytic converter's efficiency (cleaning method)

California98Civic · 06-14-2018, 10:04 PM

P0420 code (catalyst efficiency) is intermittent but persistent. I can clear it and shut off the CEL but if it takes a day or a couple weeks it always comes back.

By August 2, I have to have a successful SMOG test. So this is the perfect chance to test the efficacy of the cleaning method in the OP.

Suggestions? (take a look at the OP).

Also, I think I will try swapping the upstream and downstream O2 sensors in one last test to see if I have an intermittent sensor failure. Bad idea?

06-14-2018, 10:04 PM	#46 (permalink)
California98Civic Cyborg ECU Join Date: Mar 2011 Location: Coastal Southern California Posts: 6,299 Black and Green - '98 Honda Civic DX Coupe Team Honda 90 day: 66.42 mpg (US) Black and Red - '00 Nashbar Custom built eBike 90 day: 3671.43 mpg (US) Thanks: 2,373 Thanked 2,174 Times in 1,470 Posts	SMOG test coming P0420 code (catalyst efficiency) is intermittent but persistent. I can clear it and shut off the CEL but if it takes a day or a couple weeks it always comes back. By August 2, I have to have a successful SMOG test. So this is the perfect chance to test the efficacy of the cleaning method in the OP. Suggestions? (take a look at the OP). Also, I think I will try swapping the upstream and downstream O2 sensors in one last test to see if I have an intermittent sensor failure. Bad idea? __________________ See my car's mod & maintenance thread and my electric bicycle's thread for ongoing projects. I will rebuild Black and Green over decades as parts die, until it becomes a different car of roughly the same shape and color. My minimum fuel economy goal is 55 mpg while averaging posted speed limits. I generally top 60 mpg. See also my Honda manual transmission specs thread.