Mercedes-Benz E-Class S211 W211 Brake Servo Master Cylinder A0004300312

Mercedes-Benz E-Class S211 W211 Brake Servo Master Cylinder is a brake booster component designed for the E-Class W211/S211 generation models. It is responsible for stable vacuum generation and precise brake force modulation, which translates into safer and more predictable vehicle behavior during braking. A used OEM part is a sensible choice for professional brake system repairs in Mercedes vehicles.

Specifications and technical data

• SKU: A0004300312
• Mark: Mercedes (Genuine OE)
• Condition: Used
• OEM Part Number: A0004300312
• Substitutable numbers: A0004300312, A 000 430 03 12, A2114300302, A 211 430 03 02, EM
• Category: Brake Servos

Purpose and function in the brake system

The brake servo master cylinder in a Mercedes E-Class W211/S211 is responsible for assisting the pressure applied to the brake pedal, allowing the driver to achieve effective braking with less effort. A properly functioning servo stabilizes system pressure, improves brake force modulation, and reduces the risk of increased vehicle stopping distances.

In practice, this means more predictable car behavior in emergency situations, better vehicle control during hard braking, and a clearly perceptible, consistent brake pedal engagement point.

Benefits of using an original Mercedes servo

Choosing an original brake servo master cylinder from the Mercedes group ensures:

• retention of the factory brake pedal operating characteristics,
• compatibility with the vehicle's hydraulic system and electronic safety systems,
• appropriate boost performance under typical operating loads,
• consistency with other brake system components in the specific model.

As a result, the brake servo master cylinder can be used both as a replacement part for standard repairs and for more extensive brake system restoration in a Mercedes E-Class.

Component condition and practical service application

The offered item belongs to the Brake Servos and Proportioning Valves category and is intended for reinstallation by a service center or workshop specializing in the Mercedes brand. A used OEM component allows for cost-effective repair while maintaining the correct operating parameters of the brake system, provided that the entire system is properly installed and bled.

Before installation, it is recommended to follow standard leak test procedures, check the proper operation of the control valve, and verify compatibility with the brake master cylinder and the ABS/ESP system of the specific vehicle.

Expansion and modernization of the Mercedes brake system

If you are planning a comprehensive repair or upgrade of the braking zone in your Mercedes and need other components from the same group, such as additional servos, brake proportioning valves, or assist elements, check out the available parts in the Mercedes Brake Servos and Proportioning Valves category.

Technical support and service knowledge

When working on safety-critical systems – such as brakes, air conditioning, or heating – it is crucial to use proven service procedures and select appropriate used OEM components. To better plan vehicle maintenance and understand the relationships between individual systems, it is worth reading the guide article Air conditioning and heating – parts selection and maintenance for year-round comfort, which helps organize your approach to vehicle operation and servicing in the long term.

Summary

Mercedes-Benz E-Class S211 W211 Brake Servo Master Cylinder is a practical solution for users and workshops looking to restore proper brake system operation in this generation of E-Class vehicles. The original design, fitment for the specific platform, and the ability to integrate with the existing installation make this component a solid foundation for professional repair and maintaining the proper level of safety during daily vehicle operation.