Genuine OEM Audi Engine Coolant Hose, part number 4M0145909AD. This essential hose is a key component of the engine cooling system, responsible for transferring coolant between major engine parts, such as the radiator and the engine block. It plays a critical role in maintaining the engine's optimal operating temperature. Located as a primary connection in the cooling circuit, it handles significant coolant flow. Constructed from high-quality, reinforced rubber, this hose is designed to withstand high temperatures and pressures. Choosing a genuine OEM coolant hose guarantees the exact shape, correct routing, and material integrity for a secure, leak-free connection and reliable cooling performance.