P0420 Chevrolet -

Question

I drive an 03 Chevy Silverado. The check engine light is on and the code is P0240. The truck is not fuel efficient. Sometimes the engine light will flash and when it is the truck runs very bad. No power, very rough idle. The other morning on my way to work in a downpour this happened. I just kept my foot in it and after about 2 minutes the idle smoothed out and the light went back steady. Can a cat do this? Or is it something that would be continuous? I would appreciate any feedback you can give. I'm female and don't have lots of money to spend trying to figure this out.

Answer 1

P0420 Catalyst system below threshold ( Bank 1)

This code condition is a result of the rough idle and the vehicle not being in fuel control, When a CK ENG LT flashes this represent a misfire that is catalyst damaging. Misfire can be from the sparkplug ignition wire to the ignition coil. What you will need is a major tune up with sparkplug, sparkplug wire and maybe 2 or 3 ignition coils.