I have the P0420 code and I have replaced the bank 1 o2 sensor. what do I do now?

Question

I recently replaced my Bank 1 O2 sensor due to the P0420 code and It has come back on. The engine runs smooth, no missing or cutting out. Although it gets poor fuel mileage. Im thinking because it's a 5.2 L engine. What should I do to fix this problem? I used a Bosch O2 sensor.

Answer 1

Hi there,

If replacing the rear O2 sensor didn't work then the catalytic converter will need to be replaced to resolve the issue. It's not cleaning the exhaust enough to make the computer happy, that means the converter simply is no longer doing it's job.