P0420 Buick - where should i start ?

Question

P0420 Buick - i have a 2000 Buick and the code came up p0420 catalyst system bank 1 low efficiency where should i start ?

Answer 1

Hi there,

With this code I usually start by clearing the code and finding a different gas station. This is because sometimes the fuel additives can cause the code to come up. If the code comes back, then you have to check the exhaust system for leaks and use a scan tool to monitor the rear O2 sensor. If the voltage doesn't come up to 1 volt with a smooth but slow switch, then the converter is not doing it's job and will need to be replaced.