Tighten Fuel Cap Message And Check Engine Light

[snorydermb]

I have a 04 2500 hd and my tighten fuel cap message keeps coming on,Ive replaced the cap with a new one but I keep getting the message on my dash.I have had the check engine light cleared and Im good for a while but then it comes on again could this be a different problem than the cap?

[Draenor]

What are the actual DTCs? There are several that pertain to the EVAP system.

[62handler]

Need DTC's to know for sure but you probably have a verry large evap leak or malfunction of the system. Most of the time on GM's its the canister vent solenoid but you need to do a smoke test to be sure, so unless you have a smoke machine and a scanner to close the vent solenoid you are probably going to have a shop look at this one.