I have an nissan maxima 07 what should I do first when I have a po420 check engine light?

Question

What should I do first when I have a po420 code.

Answer 1

Hi there,

Typically the first thing I do is clear the code and see if it returns. If it does, then it's best to check the rear O2 sensor to make sure it's working properly, if it is, then you will likely need the bank 1 converter replaced.