P0420 Cadillac -

Question

2002 deville shows p0420 in history will not reset driven over 1000mi no light but cant get inspected with code in history what do I do??

Answer 1

P0420 Catalytic below efficiency Bank 1

If this is a history code and there is no CK ENG LT,   and the montor are complete you can go to your emission test. , It is the pending codes and the monitor that matter in the emission test not the history.