DTC P0449: EVAP Vent Valve Performance: Description
WARNING: This page is about a different car, the 2003 Pontiac Aztek and 2003 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.
An ignition voltage is supplied directly to the Evaporative (EVAP) emission canister vent valve. The Powertrain Control Module (PCM) 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 PCM monitors the status of the driver. If the PCM detects an incorrect voltage for the commanded state of the driver, DTC P0449 sets.
The table illustrates the relationship between the ON and OFF states, and the OPEN or CLOSED states of the EVAP canister vent valve. See EVAP VALVE COMMAND table.