Roll Over Valve (ROV)
WARNING: This page is about a different car, the 2018 Jaguar XE and 2017 Jaguar XE. However, it is still accessible from the selected car via links, so may be relevant.
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. An internal breather hose connects the ROV to a fuel vapor pipe connection on the fuel pump module flange. The fuel vapor is then routed to the evaporative emissions canister where it is stored before being purged at intervals to the engine's intake manifold.
For additional information, refer to: Evaporative Emissions .