Genuine OEM Volkswagen Auxiliary Heater Coolant Pipe, part number 5QB815101B. This pipe is responsible for circulating engine coolant to and from the auxiliary heater unit, facilitating additional cabin heating. It forms a critical part of the vehicle's heating and cooling system, ensuring proper heat exchange. This coolant pipe assembly weighs 1.071 kg and measures 0.525 m in length. Using a genuine OEM coolant pipe guarantees correct routing geometry, material resistance to heat and pressure, and leak-proof connections, which are vital for the reliable operation of the heating system and engine cooling.