P0420 1997 civic lx

[Rockman555]

I have a 97 civic lx and I got the code that the rear oxygen sensor was bad...

I was planing on replacing it so I reseted the CEL and probably two weeks later I got a PO420 code and no loger didi I get the o2 sensor code

What do you guys think might replacing the sensor fix the problem or should I just replace the cat.
I dont know anything about cars so try to explain with detail.

 

[Kensai]

So what's the PO420 code? I'd replace the sensor first, those things are cheap. See if that fixes the problem then go from there...

 

[RonJ]

P0420 is not an O2 sensor code. It indicates an exhaust leak or bad cat.

 

[Rockman555]

P0420 is not an O2 sensor code. It indicates an exhaust leak or bad cat.

HOW DO YOU CHECK FOR EXHAUST LEAKS

 

[RonJ]

Turn off the caps lock.

Look for holes or cracks in the any part of the exhaust system. As the system consists of multiple components bolted together, also check for loose connections. By the way, some muffler shops may do an exhaust system inspection for free. Just call around.