Hello,

I bought a 97 Civic which had a b18 swap done. I drove it for the first week with no problems, then the check engine light(CEL) with the code P0420. The guy at autozone that ran the code told me its probably the primary 02 sensor. So I got a direct fit 02 sensor from amazon and swapped out the pre cat 02 sensor. Then cleared the CEL and after driving 50 miles the CEL came back on. I then figured it was the cat converter, so I got the cat replace and drove it over 100 miles before the CEL came back on. Im not sure what the problems is.

Any ideas or comments?
would be greatly appreciated.

 

have you tested the rear o2 sensor?

 

Sorry, i didn't mention it before. I have also swapped the rear 02 sensor with the one I bought from amazon,but the light came back on after about 50miles.

 

what cat did you get?

 

Sounds like the car is running poorly and causing the o2 to either go bad or not read because it's covered in crap

 

 

I got a OBD II high flow weld-on cat.