Genuine OEM Audi Auxiliary Coolant Radiator, part number 4M0121212D. This component provides supplementary cooling capacity, working in conjunction with the main radiator to maintain optimal engine operating temperatures under various conditions. It is typically located in the engine bay, often alongside the main cooling system components. Constructed with an aluminum core and durable plastic end tanks, it weighs 1.09 kg and measures approximately 0.345m in length. A genuine OEM auxiliary radiator ensures precise heat exchange efficiency, proper fluid flow, and resistance to corrosion, which are vital for preventing engine overheating and ensuring long-term reliability.