Pressure control solenoid valve
WARNING: This page is about a different car, the 2012 Subaru Forester. However, it is still accessible from the selected car via links, so may be relevant.
PCV controls the fuel tank pressure to be equal to the atmospheric air pressure. Normally, the solenoid is set to OFF. The valve opens and closes mechanically in accordance with the pressure difference between tank and atmospheric air, or tank and canister.
The valve is forcibly opened by setting the solenoid to ON at the time of diagnosis.