We obviously made a bad purchase on a 2001 Honda Civic. It has 120,000 miles on it, but it burns a lot of oil. Probably about a quart every 1200-1500 miles. The check engine light recently came on, and I don’t remember the exact error code, but it had to do with the catalytic converter system efficiency. I read it typically deals with a problem regarding the rear oxygen sensor readings, and I suspect the catalytic converter is clogged due to the oil consumption. I read some posts about cleaner you can put into the gas tank from auto parts store. I also read posts were people were dumping in a gallon of lacquer thinner into the gas. I could see that damaging some sensors though. Does anybody know if these work without creating other problems? Is there a decent way to clean the catalytic converter? I really don’t want to put any more money in this car. Thanks

 

Normally catalyst below efficiency code means the cat is bad.

https://www.rockauto.com/en/catalog/honda,2001,civic,1.7l+l4,1373217,exhaust+&+emissio n,catalytic+converter,5808

the cheapest carb compliant is 250 and if you're not in ny or ca then you can just get the cheapest option altogether

https://www.hondapartscheap.com/auto...aust-pipe-scat

Have you confirmed you have no oil leaks ? 120k is really low to be burning that much oil

 

The suggestions you posted are not good ideas. Could lead to sensor damage and won't do a thing for the cat.

Studies show citric acid bath at 80 degrees F for 8 hours can revitalize aging cats.

More recent studies show citric acid with oxalic acid soak is effective in bring diesel cats back to 80% efficiency.




Here is, I believe, the original study:
https://www.ncbi.nlm.nih.gov/pubmed/16570632

It should be noted, to do it like the study, this is a two soak process, once in citric acid then another in oxalic acid.

Found the full Thesis paper published:
https://www.diva-portal.org/smash/ge...FULLTEXT01.pdf

 

Thanks for the responses. I agree this is low mileage to have this much oil consumption, but I don't believe it's leaking - the spot under the car is clean, but the tailpipe is really sooty. I've had several Hondas in the past, and I'm really disappointed in this car.

Thanks for the info on cleaning the catalytic converter, TomCat39. At this point, I don't think I'm not going to screw with this car - I'll just sell it for a loss.