P0420 Catalytic below threshold
Before the catalytic is replaced, the fuel trim and the function of the 02 sensor has to be inspected first this would be to your advantage.
Here the location of the catalytic convertor
The downstream 02 sensor should be inspected prior to replacing the catalytic convertor. Here a downstream 02 sensor that is faulty has set a catalytic convertor code.
The downstream 02 sensor replaced, This resulted in correcting a false catalytic convertor code, A functioning catalytic convertor will have the downstream 02 sensor being above 650 mv .
33.7k questions
32.5k answers
1.3k comments
23.0k users