MAINTENANCE AND SERVICE Coolant fluid VESPER Engine coolant expansion tank Press the unlocking clip to remove the coolant replacement cap and see the engine and high voltage battery coolant expansion tank. Do not open the expansion tank cap when the coolant is still hot after the vehicle is shut down. high voltage battery coolant expansion tank The coolant level should be checked occasionally while the vehicle is parked on a level ground and the engine is cold to make sure the coolant level is between the MIN and MAX marks. 257