I have a light on that says "check gas cap" and the service engine soon light is also on. Don't know why--just started today. I don't drive the car much anymore--only 2 days a week to work on Tuesday and Thursday.
The onboard diagnostic system gave me a check radiator cap notice. I check the cap and it was screwed on firmly. Apparently the cap is getting worn and it intermittently compromises the "Closed system". I have not had to replace the cap yet and the light has not come on in quite awhile. Until it comes on and stays on, I'll keep the old cap.
Engine code is diagnosed as a gas cap problem several previous times. However, the last 2 times this has happen a new gas cap from the dealer was installed. Not sure what to do next to fix the issue!