Shut-off valve, rollover
WARNING: This page is about a different car, the 2001 Saab 9-3. However, it is still accessible from the selected car via links, so may be relevant.
The rollover shut-off valve closes only in the event of the car rolling over and thereby prevents fuel leakage.
The valve is connected to the EVAP canister by a pipe. Expanding fumes from the tank are vented through the valve and the EVAP canister.