EVAP Canister Vent Valve
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 canister vent valve controls the flow of fresh air that passes through the EVAP canister. The vent valve is normally open. The PCM will command the EVAP canister vent valve closed during some EVAP tests, in order to seal the EVAP system for leak diagnosis.