VW Engine Coolant Thermostat Housing - Genuine VW 03H121117B

Product Information

The engine coolant thermostat housing is the component that houses the thermostat, which regulates the flow of coolant to and from the engine. The thermostat housing connects the engine to the radiator via hoses and helps control the engine’s operating temperature by opening and closing based on coolant temperature. In some vehicles, the thermostat housing also has additional connections for sensors or other cooling system components.

• Coolant Leaks: A common sign of a failing thermostat housing is a coolant leak. This can happen if the housing becomes cracked, or corroded, or if the gasket that seals the housing fails.
• Engine Overheating: If the thermostat housing is damaged or the thermostat inside it is stuck in the closed position, it can prevent coolant from circulating properly through the engine.
• Erratic Temperature Readings: A malfunctioning thermostat or housing can cause the engine’s temperature to fluctuate. You may notice that the temperature gauge on the dashboard moves unpredictably, indicating that the coolant flow is not being properly regulated.

About Genuine VW

The Volkswagen Group, also known as “VAG”, consists of Volkswagen, Audi, Lamborghini, Bentley, Bugatti, Porsche, Ducati, MAN, Scania, SEAT, and Skoda. The original parts used by VW to build your car are available as replacement parts under the “Genuine VW” brand. Manufactured under the direction of VW, expect excellent quality and a premium price since these parts are available exclusively through the VW Dealership network.

You may not realize this, but the parts that make up your VW are not necessarily manufactured by VW. No cause for concern, as VW designs the part, hires a manufacturer, and ensures its quality to you. In fact, many of these manufacturers have been making parts for VW for decades. In our industry these manufacturers are called OEM (Original Equipment Manufacturers), and these are often brands you recognize, including Lemforder, ZF, Sachs, Bosch, Valeo, Zimmermann, Siemens VDO, Corteco, and more. Don’t be surprised to open that Genuine VW parts box and find an OEM branded part inside, simply with the addition of a VW logo.

Be sure to keep an eye out for OE tags on our product pages to quickly identify parts coming directly from OE manufacturers. That extra bit of insight could save you some serious money while shopping! Refer to our OE Academy for further information regarding the OE/OEM tags throughout the site.