Genuine OEM Volkswagen Engine Coolant Thermostat, part number 03H121113E. This vital component precisely regulates the flow of coolant through the engine, maintaining the optimal operating temperature for peak performance and fuel efficiency. It is typically located within the engine cooling system, often near the engine block or cylinder head. Constructed with a robust metallic body, a calibrated spring, and a durable rubber seal, it weighs approximately 0.118 kg. Installing a genuine OEM thermostat ensures accurate temperature control, prevents engine overheating or undercooling, and provides reliable, long-lasting operation.