Wrong PO420 is his CATALYTIC CONVERTER IS BAD!!! That is only thing wrong!
Quote Originally Posted by Atlblkz06
Sometimes the CEL will come back on after you replace the O2 sensor.

Give it a day or two after replacing the O2, it should go away.

Dont trust the computer to give you the right bank. I say just replace both of em. If one is dead, the other one cant be too far behind.

Good luck!