Roll Over Valve
WARNING: This page is about a different car, the 2018 Land Rover Range Rover, 2017 Land Rover Range Rover, 2016 Land Rover Range Rover, 2015 Land Rover Range Rover, and 2014 Land Rover Range Rover. However, it is still accessible from the selected car via links, so may be relevant.
The Roll Over Valve (ROV) allows vapor to escape to prevent tank pressurization in normal vehicle operating modes. However this valve is designed to close to prevent fuel leakage through the vent in the event of a vehicle roll over.