Rain Sensor Mercedes SLK R172 W204 Front Windscreen Control Unit A2049017901

The Mercedes SLK R172 W204 Rain Sensor is a precise component from the electronic control units category, responsible for the automatic operation of the front windshield wipers. A properly selected sensor ensures stable system performance, improves driving comfort, and allows for full utilization of Mercedes vehicle equipment functions.

Specifications and technical data

• SKU: A2049017901-1
• Mark: Mercedes (Genuine OE)
• Condition: Used
• OEM Part Number: A2049017901
• Substitutable numbers: A2049017901, A 204 901 79 01
• Location on the vehicle: Front
• Category: ECUs & Computer Modules

Purpose and Function of the Mercedes Rain Sensor

The rain sensor for Mercedes SLK R172 and W204 models works in conjunction with the wiper system and body electronics, analyzing the amount of water on the windshield. Based on the signal from the sensor, the control unit adjusts the wiper frequency, which translates to:

• automatic adjustment of wiper speed to the intensity of rainfall,
• improved visibility in varying weather conditions,
• relieving the driver from manually switching wiper speeds.

Its placement at the front of the vehicle allows for direct reading of conditions on the windshield, increasing the precision of the entire system.

Electronic Control Unit – Technical Characteristics

The presented component belongs to the Electronic Control Units and Controllers category, meaning it acts as an active sensor integrated with the vehicle's electrical system. In practice, this means:

• integration with the factory comfort system and body control module,
• precise processing of optical signals from the glass surface into electrical signals,
• compatibility with the Mercedes electrical architecture for the specific model generation.

This solution ensures full functionality of the vehicle's equipment, including the automatic wiper mode and interaction with other comfort systems, if provided for in the vehicle's configuration.

Benefits of Using an Original Rain Sensor

Choosing an original Mercedes rain sensor offers a range of practical advantages in daily operation:

• factory fit for windshield and bracket – proper adhesion to the glass surface and correct positioning at the front of the vehicle,
• stable communication with the electrical system – no need for wiring modifications or additional adapters,
• consistent performance in various conditions – from light drizzle to heavy downpours.

This ensures predictable wiper system response, and the driver maintains full control of the vehicle without distraction from manual operation.

Item Condition and Practical Application

The offered rain sensor is a used part, allowing for an attractive purchase price while maintaining operational parameters consistent with the manufacturer's original specifications. This is a good solution for:

• repairs after windshield replacement, when the previous sensor was damaged,
• diagnosing wiper system errors related to incorrect rainfall detection,
• restoring full equipment functionality in vehicles after a collision or intervention in the electrical system.

Before installation, it is recommended to verify compatibility with the specific vehicle equipment version and perform control unit adaptation if required by the particular model.

Mercedes Electronic Control Units – Selection and Technical Knowledge

If you are looking for other Mercedes Electronic Control Units and Controllers, check out our dedicated offer: Mercedes electronic control units and controllers. You will find a wide selection of used parts that allow for economical servicing of comfort and safety systems.

When working with vehicle electronics, it is advisable to use reliable sources of knowledge. See the article on our blog, where we discuss practical aspects of repairing modules and multimedia systems using an example from another brand: how to care for electronic systems and modules using used parts. This is a good supplement to your knowledge when planning repairs of control systems in modern cars.