This seems to be a common problem with HHRs. I've replaced gas caps, taken it to the dealer and nobody can find any issues. They reset the codes and it will stay off for awhile and then come back on. I've just learned to live with it.
Engine light came on - checked gasoline tank cap - blew it off to clean - replaced it and light went off - has periodically come on again and then goes off again - some brands of gasoline also seem to cause it to come on -
The gas cap has been replaced three times. A smoke test was done originally to diagnose the problem. It appears that the gas caps don't 'really' fit this vehicle. So, I wouldn't really care, but the auto-start cannot work without that damn engine light off, so the one thing that worked on this pos, now can't work. We will NEVER buy another GM product.
Check engine light comes on replaced gas cap went out for quit awhile but now it is one again. Dealership said there is a bulletin out. Car runs fine and there is no performance loss. One dealership wants to clean injectors for $240 but i really don't think thats the problem Any Ideas???? Karl