Canister Vent (CV) Solenoid
WARNING: This page is about a different car, the 2006 Mercury Mariner and 2006 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.
During the EVAP leak check monitor, the CV solenoid seals the EVAP canister from atmospheric pressure. This allows the EVAP canister purge valve to obtain the target vacuum in the fuel tank during the EVAP leak check monitor.
Courtesy of FORD MOTOR CO.