I have P0053 and P0420 Code, what could it be?

Question

The front catalytic converter manifold has been replaced. the Upstream O2 sensor has been replaced. Should I replace the downstream O2 sensor? Could there be other issues?

Answer 1

Hi there,

The code can be a result of the down stream O2 sensor, if it's not reading properly it will cause a fuel mixture change that can cause the vehicle to run richer, if it's running to rich then the converter can't clean the exhaust and you will get this code.

I would replace the sensor if you don't have a scan tool to watch it.