2004 Pontiac Grand Prix Q&A
2004 Pontiac Grand Prix Question: check engine light is on. I get a message to check gas cap.
If the lamp has not gone out after a few days you will need to have a service shop or dealer run a diagnostic test on the fuel evaporative system. The onboard fuel emmisions system test itself for possible evaporative leaks in the fuel tank and lines. It has turned the light on because a sensor indicates the system will not hold pressure. This is not a safety issue...and emmisions issue. - milesauto
I've owned this car for 4 years now and since I bought it I've replaced the gas cap 5 times try...