Need some help guys, please. Check Engine light problem

[2004YukonXLDenali]

Here is my problem. The check engine light comes on when the gas gauge is below 3/4 of a tank. After I fill the tank all the way up the check engine light turns off. I changed the gas cap hoping that was the problem but the issue still persists. If you guys have any solution ideas I would be very greatful. Im not sure the gas level is the reason for the check engine light but it seems to be?.. Hope to hear from you guys soon. Take care.

 

[Clemsonbloz]

get scanned so you can get the code number.. most likely something to do with the evap system

 

[Eagle]

my guess as well.