i've got a 03 dakota ext cab 4.7 4x4 auto. had a code p0456 a week ago and found out my gas cap was loose. cleared the code and everything was fine. last night i got a code p0442. are there any easy fixes for this? i already checked the cap to make sure it was tight. i'm not sure how the evap equipment is setup on these trucks and could use some help. truck still runs perfect but the light is annoying. thanks in advance