1. Make sure the gas cap is tight
2. Check the condition of the rubber hoses that connect the lines to the charchol canister.
If they are cracked or checked at all, replace them. This has been a common DTC with many of the "few" years old rams. If its under warranty yet, have the dealership do it. I had the same problems with mine but it turned out to be the wire that fires the solenoid rubbing on one of the front end components (< not common). most often its the rubber connection lines at the canister