Check Engine light on 2003 Cadillac Escalade

Check engine light comes on when the gas tank is below 1/2. Replaced gas cap and that seemed to help for awhile, but its doing it again? Any ideas?

Asked by for the 2003 Cadillac Escalade
Have you had the computer checked for codes? If not, I would start with that.

A computer code helps you know where to start testing.

Some of the retail parts stores will check your codes for free.