3500 HD Dualley Silverado
TRK has 137K miles. Replaced DEF heater, visited Dealer for them to flush system and reset codes. Three weeks ago.
I changed the fuel filter messages appeared and disappeared. Drove over 175 miles. TRK set over night. Started up this morning (Temp about 55 degrees) and at idle the check engine light appeared on dash. I had one message telling me I have an emission issue, correct with in 175 miles. I drove 175 plus miles at 75 miles per hour. No codes, ran/runs great. Would anybody have an idea? When I primed the system after changing the fuel filter, the primer was still able to be pressed when air remover. Is it possible there is air in the fuel system?