GMC Troubleshooting Questions? Ask a Mechanic for Answers
just a 300 code ?
when the light comes on do you feel the engine misfire ?
how does it run other than the check engine light ?
if the light did not come on would you know there was anything wrong ?
is there any chance when it would not restart was it tested for spark when cranking it over ?
would it somewhat run on starting fluid being sprayed into the throttle body butter fly ?
when this will not start and the engine physically cranks over it is missing spark or fuel
and once we know which we are missing it will narrow down the problem area
get it to act up and not start see on the live data when cranking it over if there is a crank RPM registering
see if the engine will somewhat run on starting fluid and also check for spark out of the coils when cranking it over