EVAP Pressure Switching Solenoid
WARNING: This page is about a different car, the 2003 Pontiac Vibe. However, it is still accessible from the selected car via links, so may be relevant.
The EVAP pressure switching solenoid opens the evaporative line between the fuel tank and the EVAP canister. When the EVAP pressure switching solenoid is closed, air is blocked from entering the tank side of the system.