Genuine OEM Audi Engine Thermostat Housing, part number 03C121111T. This assembly houses the engine thermostat and is responsible for regulating the engine's operating temperature by controlling the flow of coolant through the cooling system. Weighing approximately 0.658 kg, this component is crucial for engine efficiency and longevity. Choosing a genuine OEM thermostat housing ensures precise fitment, proper sealing, and accurate temperature regulation, which are vital for preventing engine overheating or undercooling and maintaining optimal performance.