Genuine OEM Audi Coolant Regulator Housing, part number 03C121111G. This housing is a crucial part of the engine cooling system, designed to enclose the thermostat and manage the flow of coolant throughout the engine. It is typically located near the engine block or cylinder head, connecting to various coolant hoses and the radiator. Constructed from durable materials to withstand engine heat and coolant pressures, it weighs approximately 0.66 kg. Using a genuine OEM coolant regulator housing ensures precise fitment, proper sealing, and accurate thermostat operation, which are essential for maintaining correct engine operating temperatures and preventing overheating.