Genuine OEM Jaguar Coolant Expansion Tank, part number C2Z29118. This essential component manages the changes in coolant volume that occur as the engine heats and cools. It is an integral part of the engine cooling system, providing a reservoir for excess coolant and maintaining system pressure. Constructed from durable, heat-resistant plastic, it includes a factory-specified pressure cap. Using a genuine OEM expansion tank ensures correct material composition and pressure relief valve calibration for reliable cooling system performance.