Genuine OEM Audi Coolant Regulator Housing With Thermostat, part number 057121111C. This essential engine cooling component houses the thermostat and precisely regulates the flow of coolant through the engine. It is critical for maintaining the engine's optimal operating temperature, preventing both overheating and undercooling. Weighing 0.329 kg and measuring 0.125 m in length, this assembly is engineered for exact fitment and thermal performance. Choosing a genuine OEM housing ensures correct material integrity, sealing surfaces, and thermostat calibration for reliable engine temperature management.