Genuine OEM Audi Coolant Breather Line, part number 8W0121081EE. This essential component plays a vital role in the engine cooling system by allowing trapped air to escape, preventing the formation of air pockets that can hinder coolant circulation and lead to overheating. It is typically a small diameter hose connected to the expansion tank or other high points in the cooling system. Constructed from durable, heat-resistant rubber or plastic, it measures approximately 22.5 cm long. Opting for a genuine OEM breather line ensures correct material composition, precise routing, and reliable performance, crucial for maintaining optimal engine temperature.