97 Mazda protege 156,000 mi. i got a p0420 trouble code. Could a catalytic converter be making my car run rough? it only runs rough in the cold morning or when the car hasn't been driven or a while. Does this mean i need a tune up or do i have an internal problem? The engine makes no weird noises or anything else.
Mar 6, 2007 at 6:17 AM