Mercedes W203 C209 Roof Alarm Motion Sensor Module Cover Trim Beige A2038219751

Visual condition of the part

The product shows signs of use visible in the photos.

Mercedes W203 C209 Roof Alarm Motion Sensor Module Cover Trim Beige is an original component from the Electronic control modules and controllers group, designed for installation in the rear part of the vehicle body. This carefully designed beige cover allows for the aesthetic and functional protection of the alarm sensor, supporting the proper operation of the vehicle's factory security system.

Specifications and technical data

• SKU: A2038219751-3
• Mark: Mercedes (Genuine OE)
• Condition: Used
• OEM Part Number: A2038219751
• Substitutable numbers: A2038219751, A 203 821 97 51
• Location on the vehicle: Rear
• Color: Beige
• Category: ECUs & Computer Modules

Purpose and function of the alarm sensor cover

The alarm sensor cover in Mercedes W203 and CL203 models is responsible for the stable, mechanical protection of the alarm system's detection element in the rear of the vehicle. It protects the sensor against accidental impacts, dirt, and unauthorized access, while ensuring optimal operating conditions for the electronics – without obstructing the detection field or interfering with the system's sensitivity.

Precise fitment for this specific generation of Mercedes reduces the risk of mounting looseness, squeaking, or vibrations, which is important for both acoustic comfort and the long-term reliability of the alarm system.

Color scheme and interior integration

The beige finish of the cover allows for seamless integration into the factory interior styling or rear trim. As a result, the cover is unobtrusive, and the sensor remains discreetly hidden, which is beneficial from both an aesthetic and functional standpoint.

Choosing the correct color is important for post-accident repairs, replacing damaged upholstery elements, or restoring the original look of the cabin – especially in vehicles where maintaining consistent factory color schemes is a priority.

Compatibility and role in the electronic system

As an element from the Electronic control modules and controllers group, the cover works directly with the alarm sensor, which is part of the vehicle's broader electronic architecture. Properly securing the sensor in the dedicated cover helps maintain a stable operating position, which translates into consistent readings and a reduction in false alarm triggers.

A properly selected cover is particularly important when servicing security systems, such as when replacing upholstery elements, wiring harnesses, or control modules – it allows for the maintenance of factory installation routing and correct component placement.

Condition, origin, and service application

The component comes from a Mercedes vehicle and is intended for re-installation in W203 and CL203 models in the rear part of the body. A used component of this type is a sensible solution for maintenance repairs where the priority is to maintain original mounting geometry and compatibility with the factory design.

The alarm sensor cover is suitable for both local repairs following mechanical damage and comprehensive interior restoration, where it is necessary to restore the full functionality of the alarm system using original design solutions.

Support in selecting electronics and accessories

When working with security systems and other onboard electronic components, it is worth using reliable sources of information. Detailed information on how to safely select and install used modules and sensors can be found in the Global Parts guide: Used automotive electronics on board – why is it worth choosing second-hand ECU modules and sensors?

If you are planning a comprehensive repair or upgrade of the electronic security system zone in your Mercedes and need other elements from the same group, such as control modules, controllers, or additional sensor covers, check out the available parts in the Mercedes electronic control modules and controllers category.