2006 GMC Sierra V8 with engine code P0449

Question

I replaced vent solonid, gas cap, and sensor and reset computer. Light stays off until i cut truck off then it comes back on. Help please

Answer 1

P0449 Evaporative emission (EVAP) vent solenoid control circuit

The control part of the vent control solenoid will need to be tested from the ECM, where the ECM sends a ground for a command to the solenoid vent, The first inspection is to check its fuse, this is a fuse protected vent solenoid, in the engine fuse/relay box check the fuse for this should be listed as 4WS (depending on the VIN)