Genuine OEM Audi Engine Coolant Tank, part number 8W1121405N. This essential component, located on the left side, holds and stores excess engine coolant, allowing for thermal expansion and maintaining proper system pressure. Constructed from durable plastic and weighing 0.86 kg, it is designed to withstand temperature fluctuations and chemical exposure. Choosing a genuine OEM coolant tank ensures a precise fit, leak-free operation, and long-term reliability for your engine's cooling system.