Genuine OEM Audi Coolant Reservoir Hose, part number 5N0121109E. This hose is a critical component in the engine cooling system, responsible for transferring coolant between the reservoir and other cooling system parts. It is typically located at the front of the engine bay. This rubber hose measures approximately 295mm in length. Choosing genuine OEM ensures the correct routing geometry, material resistance to heat and coolant, and leak-free performance for optimal engine temperature regulation.