Many Major National Auto Parts Stores Will Read Your Engine Codes For Free In Their Parking Lot. Get Them Read And Write Them Down. Post Them Here.
I will say that if you’ve got a DTC (diagnostic trouble code) P0456 (EVAP system small leak) and your truck was built on or between 01/26/07 and 06/18/07 then the condition could be caused by loose charcoal from a Fuel Vapor Canister.
A sticker on your driver’s door or door opening should have a mfg. (manufacture) date month/year. You can see if it is possibly within the range given.
Dodge/Jeep published a 3 page TSB (Technical Service Bulletin) #25-003-07, pertaining to 2007 Ram Truck, Durango/Aspen, Grand Cherokee, and Commander vehicles, to help their technicans diagnose and repair these vehicles.
There is a flow chart and procedures given in the bulletin, including a flow and smoke test.
The fix for vehicles that require it is a new (revised part ?) EVAP Fuel Vapor Canister, EVAP fresh air hose, and EVAP fresh air filter. Part numbers are listed (different for 26 gallon tank or 34/35 gallon tank).
Get us the code(s). Check the mfg. date.
Who did your smoke test and vacuum checks ?
CSA