DTC P0449: EVAP Vent Valve Performance: Description
WARNING: This page is about a different car, the 2002 Chevrolet Corvette. However, it is still accessible from the selected car via links, so may be relevant.
An ignition voltage is supplied directly to the EVAP canister vent valve. The control module controls the EVAP vent valve by grounding the control circuit via an internal switch called a driver. The primary function of the driver is to supply the ground for the controlled component. The control module monitors the status of the driver. If the control module detects an incorrect voltage for the commanded state of the driver, DTC P0449 sets.