Genuine OEM Audi Coolant Hose, part number 3D0121101R. This essential component is designed to transport coolant efficiently within the engine cooling system, playing a critical role in maintaining optimal engine operating temperatures. It is positioned connecting to the coolant expansion tank and other lines in the cooling circuit. Weighing approximately 0.12 kg, this hose is engineered for durability and resistance to high temperatures and pressures. Choosing a genuine OEM coolant hose ensures correct routing geometry, resistance to degradation from coolant chemicals, and long-term leak-free performance, which is vital for preventing engine overheating.