Genuine OEM Audi Engine Coolant Hose, part number 4K0121109AQ. This hose transports engine coolant for thermal management, playing a critical role in maintaining optimal engine temperature. Positioned as a lower radiator hose, it connects to the radiator. Weighing 0.115 kg and measuring 0.35 m in length, its precise routing and material composition are essential for leak-free performance and long-term durability in high-temperature environments.