MY 03 Deville has check gas cap message once every 3 to 4 weeks. After resetting the computer. Its good . I tried a new gas cap. It never sets a code, Just gets the message. Any thoughts about the problem?

 

My 2008 Cadillac srx engine light came on about 2 wks before. I tightened the gas cap and it went off. Light back on a few days later on. Same thing-tightened cap light went off. Bought a new gas cap last night but didn't have a possibility to change it out.

Are there easy things to check and maybe correct the issue?

 

Tommy possibly vent or.purge solenoid, or vacuum leak.
Peter gas cap most common cause of ses but you need to be sure what code set. Evap code same as Tommy. Gas caps aren't universal anymore so you need to have correct one.