What's the code po449 GMC sierra?

The GMC Sierra's P0449 error code is technically described as a "Evaporative Emission Vent Valve Solenoid Malfunction". This means the vehicle's on-board diagnostics has detected a leak in the emissions system from irregular information gathered from the solenoid by the ECM. Possible causes include a loose gas cap, damaged or improperly fitted vacuum hoses, d***y or failed purge or vent solenoids or an EVAP vent solenoid that has stopped working and needs replaced. This code can also appear if the EVAP cannister has become fuel soaked and is no longer cleaning emissions. Loose wiring, connections and lines within the Sierra's fuel delivery system near the tank or gas cap may also contribute to the error. Drivers will experience an illuminated "check engine" light and the possible smell of fuel fumes.