my 2006 hummer3 engine light went on after I put in gas. if I didn't put the gas cap on tight enough would that cause it and if so will the light still stay on until I get the computer adjusted
Yes, a loose or missing gas cap is one of the most common causes for a CEL to come on. The emissions EVAP fault code. You don't have to get the computer, or ECU "adjusted", it may go off on it's own or can be re-set with an OBD scanner.
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