P0420 Chevrolet -

Question

My check engine light has come on, gives me the service code p0420, truck seems to drive idle and drive fine, only thing is sometimes, after sitting a bit, will stall after first crank but restart with no problem (1998 Chevrolet z71 5.7 liter 195000miles)

Answer 1

P0420 Catalytic below efficiency Bank 1

The stalling at the first start up , this is where a throttle body cleaning with a MAF (mass airflow) cleaning will really help. P0420 this is so popular with Cheverolet that replacing the catalytic should be made into a hobby.