BMW Brake Master Cylinder Reservoir - Genuine BMW 34519504021

Product Information

BMW Brake Master Cylinders diagram for M340i xDrive, M440i Gran Coupe, & more

A brake master cylinder reservoir stores brake fluid and feeds it to the front and rear brakes of a car. A failing brake master cylinder can cause a number of issues, including inconsistent brake performance, low fluid levels, and/or a low pedal.

• Brake pedal feels spongy: When the brake pedal feels soft or squishy, it could indicate air or moisture in the brake system. Low brake fluid levels, leaks, or improper bleeding can cause this.
• Brake fluid is contaminated: If the brake fluid is dark brown or black, it could be contaminated. This can happen when the rubber seals on the master cylinder wear out and break down.

About Genuine BMW

The original parts used by BMW to build your car are available as replacement parts under the “Genuine BMW” brand. When ordering a Genuine BMW part you are guaranteed to get the same part that you would pick up from your local dealerships part department. Genuine BMW parts have been built to BMW’s stringent standards and are the same quality of the original parts used to build your Ultimate Driving Machine.

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