Mercedes-Benz W211 Brake Servo Master Cylinder - Used Original Parts

Diagnosis and Common Symptoms

From the workshop floor, the most common failure point on the pre-facelift W211 and R230 chassis is the Sensotronic Brake Control (SBC) hydraulic unit. The system is designed with a pre-programmed service life, measured by brake pedal actuations. Once this internal counter reaches its limit, the control module triggers a fault to ensure safety.

Common Dashboard Warnings:

• "Brake Defective Stop Vehicle!" (Red warning)
• "Service Brake! Visit Workshop!" (White warning)

Diagnostic Trouble Codes (DTCs):

• C249F: CHECK OPERATING TIME OF COMPONENT A7/3 (SBC HYDRAULIC UNIT) - This is the most prevalent code, indicating the service threshold has been reached.
• Other pressure-related faults logged in the SBC module.

Physical Symptoms:

• A hard, unresponsive brake pedal with significantly reduced braking power as the system reverts to a basic hydraulic backup mode.
• Audible buzzing from the pump running longer than usual.

Introduction

This is a Genuine Mercedes-Benz SBC hydraulic unit, carefully removed from a donor vehicle. We understand the critical nature of this component, which is why each unit undergoes a comprehensive diagnostic evaluation to verify its operational pressure and, most importantly, to ensure its internal service counter has substantial life remaining. This provides a reliable, workshop-tested solution without the expense of a brand-new component.

Product Details

• Brand: Mercedes-Benz / Bosch
• Model Compatibility: Mercedes-Benz E-Class (W211; 2003-2006), SL-Class (R230; 2003-2006)
• Part Name: Sensotronic Brake Control (SBC) Hydraulic Unit / Master Cylinder Assembly
• Condition: Genuine Used (Tested Working)
• Notes: Part number verification is crucial for compatibility. Installation requires a full brake fluid flush and system bleed using Mercedes-specific diagnostic tools (e.g., STAR/Xentry) to correctly deactivate, install, and reactivate the SBC system. The service counter must be reset upon installation.