ABS Sensor Mercedes Vito W639 Brake Axle Suspension Rear Left N/S A6395402317

ABS Sensor Mercedes Vito W639 Brake Axle Suspension Rear Left N/S is a precision traction control component responsible for accurately reading the rotational speed of the rear left wheel. As part of the ABS speed sensor group, it works with the control module to support vehicle stability and emergency braking efficiency. This used original component is a sensible choice for professional ABS system repairs in a Mercedes W639.

Specifications and technical data

• SKU: A6395402317
• Mark: Mercedes (Genuine OE)
• Condition: Used
• OEM Part Number: A6395402317
• Substitutable numbers: A6395402317, A 639 540 23 17, BG
• Location on the vehicle: Rear, Left
• Category: ABS Speed Sensors

Function and role of the ABS sensor in the Mercedes W639

The sensor mounted on the rear axle on the left side monitors wheel rotational speed and transmits a signal to the ABS/ESP controller. Based on this data, the system can:

• limit wheel lock-up during sudden braking,
• support directional stability when traction is lost,
• ensure the correct operation of driver assistance systems that rely on wheel speed measurement.

A properly functioning sensor on the rear left side is crucial for the uniform operation of the entire system, as an erroneous signal from one wheel can cause incorrect ABS activation or warning lights on the dashboard.

Why it is worth using an original ABS speed sensor

In Mercedes W639 vehicles, the ABS system is sensitive to the quality of the signal from the sensors. Using an original component from the same design group ensures:

• a stable, repeatable signal for the controller,
• proper geometric fit to the hub and steering knuckle,
• appropriate electrical characteristics in accordance with the manufacturer's requirements.

Thanks to this, the ABS speed sensor can operate across the full range of temperatures and loads typical for the rear axle of a commercial vehicle, minimizing the risk of accidental ABS/ESP warning light activation.

Vehicle placement and installation aspects

The presented component is intended for installation on the rear left side of the vehicle. Such clear placement identification facilitates the selection of the correct component when servicing the rear axle, especially when only one sensor is being replaced.

During installation, it is worth paying attention to:

• thorough cleaning of the socket in the steering knuckle or mount,
• correct routing of the cable, maintaining factory mounting points,
• checking the condition of the pulse ring on the wheel hub.

This approach reduces the risk of mechanical damage to the cable and signal interference during operation.

Application in service practice

A used ABS sensor for the Mercedes W639 is a good solution in situations where:

• a quick and economical repair of the ABS system is necessary,
• diagnostics have shown an open circuit or a distorted signal from the rear left wheel,
• the vehicle is used intensively and restoring system functionality efficiently is a priority.

A properly selected component allows for restoring correct system operation without interfering with other brake system components, which is beneficial in terms of both cost and time.

If you are planning a comprehensive repair or upgrade of the brake system area in your Mercedes and need other elements from the same group, such as additional wheel speed sensors, sensor wiring harness elements, or related control components, check the available parts in the Mercedes ABS speed sensor category.

Safety and drivetrain diagnostics

A functional ABS sensor works not only with the brake system but also with elements responsible for power transmission and vehicle stability. In the event of concerning symptoms, such as illuminated ABS/ESP warning lights, uneven system operation, or errors stored in the controller, it is worth expanding diagnostics to include an assessment of the differential, sensors, and other drivetrain components. Practical tips on such verification can be found in the guide Second-hand differential – what you need to know about used differentials, sensors, and drivetrain systems, which helps in planning repairs consciously and reducing the risk of costly failures.