Audi VW Engine Coolant Thermostat Housing Assembly - Febi-Bilstein 04L121026AH

Product Information

Thermostats are a simple device which regulates coolant flow through the engine. When cold it will stay closed, stopping coolant flow and helping the engine warm up faster. Once up to temperature, it will open and allow normal coolant flow and maintain proper engine temperature.

For many applications, multiple temperature ratings are available. These ratings denote when the thermostat opens, and in extreme climates different temperature ratings can be used to assist the vehicle in maintaining proper temperatures. In very hot desert climates for instance, a lower temperature rated thermostat may be preferred.

There are two types of thermostat failures:

Thermostat stuck open (most common): Coolant will flow through the engine constantly from cold, preventing the engine from reaching operating temperature. Usually this means a rich mixture resulting in poor fuel mileage and potential catalytic converter damage.

Thermostat stuck closed: If the thermostat is stuck closed it will restrict flow into the engine resulting in an overheating condition, resulting in potential catastrophic engine damage.

About Febi Bilstein

Ferdinand Bilstein’s febi brand is a global leader in the replacement parts market, known for offering high-quality alternatives to original equipment (OE) parts. With a range of over 50,000 technical replacement parts for passenger cars, light commercial vehicles, and trucks, febi ensures that consumers and professionals have access to reliable solutions for maintaining and repairing vehicles. The brand is committed to staying at the forefront of automotive technology, providing parts for hybrid, electric, and hydrogen-powered vehicles, and continuously expanding its product offerings to meet the demands of the evolving aftermarket. febi’s global presence spans over 170 countries, supported by advanced logistics centers that ensure fast delivery and product availability worldwide.

A strong focus on quality sets febi apart, as their products match or exceed OE standards, backed by rigorous quality control and in-house manufacturing capabilities. febi offers comprehensive repair solutions for all major vehicle brands and models, ensuring that critical parts are readily available for professional workshops. With a deep-rooted tradition in mobility and a future-oriented approach, febi is a trusted partner in keeping vehicles performing optimally, regardless of their powertrain or application.