Audi Engine Coolant Reservoir Hose - Genuine Audi 4G0121081AH

Product Information

The engine coolant reservoir hose connects the engine’s cooling system to the coolant reservoir tank. Its primary function is to transport excess coolant from the radiator to the reservoir when the engine heats up and coolant expands. When the engine cools down, the hose also allows coolant to flow back into the radiator from the reservoir, ensuring the engine maintains the proper coolant level. This helps prevent overheating and maintains optimal engine temperature.

• Leaks: A leak in the coolant reservoir or hose can cause the engine to overheat
• Overheating: A malfunctioning coolant hose or a leaking coolant reservoir can cause the engine to overheat
• Check engine light: A faulty coolant hose can cause the check engine light on the dashboard to illuminate due to a fault in coolant temperature and level measuring systems

About Genuine Audi

The original parts used by Audi to build your car are available as replacement parts under the “Genuine Audi” brand. Manufactured under the direction of Audi, expect excellent quality and a premium price since these parts are available exclusively through the Audi Dealership network.

You may not realize this, but the parts that make up your Audi are not necessarily manufactured by Audi. No cause for concern, as Audi designs the part, hires a manufacturer, and ensures its quality to you. In fact, many of these manufacturers have been making parts for Audi 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 Audi parts box and find an OEM branded part inside, simply with the addition of an Audi logo.

Be sure to keep an eye out for OE tags on our product pages to quickly identify parts coming direct 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.