Genuine OEM Audi Coolant Expansion Tank Vent Line, part number 4G0121081CQ. This line is crucial for allowing air to escape from the coolant expansion tank, maintaining optimal pressure and preventing air pockets in the cooling system. It connects to the expansion tank. Made from durable, heat-resistant rubber or plastic, it measures approximately 0.21 meters in length. Using a genuine OEM vent line ensures precise fitment and material integrity, critical for the long-term reliability of the engine cooling system.

Catalogue entry: PIPE left front.