Hi guys, here are my problems. I just had a b16a2 swap into a 96 civic cx about a month ago. After the swap was done my cel came on and i pulled the code. It was the primary o2 sensor. I replaced with a ntk o2 sensor and i also cleaned the TB and IACV. The code for the primary sensor was gone but there's another code. The new code was for the iacv. I replaced it with my friend's b16a iacv and it works fine and the code was gone. Just the other day i was driving on the highway, the cel came on again (only comes on during highway speed). This time it was the Catalyst low efficiency P0420. What does that mean? Does it mean my cat converter is bad or the rear o2 sensor? It is a Magnaflow 2 inches universal cat converter. I brought it brand new. So i don't think is the cat converter. Would it be the rear o2 sensor that gone bad? I am sure someone had this problem before with P0420 catalyst low efficiency. How did you fix it? Any help and suggestion would be very helpful? Thanks

 

sounds like bad back o2 sensor, swap them and see if code goes away or comes up for front o2 once swapped. also check for exhaust leaks

save you a huge headache, get a obd2a to obd1 conversion plug to use a obd1 ecu and call it a day. you can use a p28 ecu and if ya want get it chipped and tuned.
the obd1 system doesnt require all the bs the obd2 system requires. and you wont have so many cells.