'gascap' warning light is on; not corrected by replacing the gascap with a new one as suggested in the owner's manual. We used a device to clear the codes and it said there was still a slight leak . .
'Check engine' light on. on 2007 Chrysler Aspen
The system will have to be properly diagnosed either using a scan tool with bidirectional controls that can open and shut evap solenoids or by using a "smoke machine" that puts inert non flammable smoke into the fuel system to look for leaks.