A Coolant Tank problem in a Volkswagen car can be very dangerous. If the coolant tank is leaking or not filled to the proper level, it can cause the engine to overheat. This can lead to engine damage, or even complete engine failure. It can also put the car’s occupants at risk of injury due to overheated brakes or steering systems. Additionally, a leaking coolant tank can lead to an environmental hazard if the coolant spills onto the ground.