03 Check Engine Light Question

[8MYROVER]

Everytime it has happend to me was because the gas cap was not on properly. Take it and have the code read. Then take off the gas cap, put it back on then turn it three full clicks after it stops. Clear the code with the reader and see if that does not solve the problem totally. (If you know anyone who has any sort of OBDII power programmer most all of them will read and clear codes, even if it is not for your model vehicle, I have even used the one from my Duramax to clear codes on the H2)