BMW 3 5 Series E39 E46 Touring Ultrasonic Roof Alarm Sensor Module ECU 6938049

BMW 3 5 Series E39 E46 Touring Ultrasonic Roof Alarm Sensor Module ECU is an original security system component designed for factory alarm systems in BMW 5 Series E39 and 3 Series E46 models. This component is responsible for monitoring the area near the roof and windows, supporting effective detection of unauthorized access to the vehicle interior. By using an OEM part, you maintain consistency with the vehicle's factory electrical and logic architecture, which facilitates diagnostics and service.

Specifications and technical data

• SKU: 6938049
• Mark: BMW (Genuine OE)
• Condition: Used
• OEM Part Number: 6938049
• Substitutable numbers: 65756938049, 6938049, 8376993, 65758376993, 65758379939, 8379939, EM
• Offset (ET):
• Category: Other Starters, Alternators, ECUs & Wiring

Function and role of the roof alarm sensor in BMW E39 / E46

The roof alarm sensor in the BMW E39 and E46 is a security system component that monitors the cabin area near the roof, pillars, and windows. It works in conjunction with the central alarm module, transmitting a signal regarding interior space intrusion, e.g., in the event of an attempted window breakage or unauthorized vehicle entry.

A properly functioning sensor:

• supports the stable operation of the factory alarm,
• reduces the risk of false alarms when the system is configured correctly,
• maintains the full functionality of the original security equipment.

Compatibility and integration with BMW installation

The offered sensor is a BMW OE part, which means it is compatible with factory wiring harnesses, connectors, and control logic in E39 and E46 models. As a result, installation is similar to a standard service replacement, without the need for wiring modifications or the use of adapters.

In practice, this means:

• maintaining the original mounting method in the headliner or roof area,
• proper cooperation with the central comfort and alarm module,
• easier diagnostics using factory BMW service software.

Condition of the part and service application

The presented roof alarm sensor is a used part, sourced from dismantling, intended for service applications as well as post-accident or maintenance repairs. This solution allows for an economical replacement of a damaged or unstable component while maintaining compliance with the vehicle's original specifications.

Replacing the sensor is particularly advisable when:

• the alarm triggers spontaneously without a clear cause,
• the system does not respond to interior space intrusion,
• diagnostics show errors related to the roof sensor or interior zone.

Benefits of using an original BMW sensor

Using an original roof alarm sensor in a BMW E39 / E46 ensures consistency with the factory security system design. Proper electrical and mechanical fitment reduces the risk of communication issues within the vehicle bus and minimizes the need for additional configuration.

Key advantages include:

• maintaining factory alarm operating parameters,
• no need to adapt universal solutions,
• easier identification of potential faults in the future.

Support with selection and related content

If you are planning a comprehensive repair or upgrade of the interior security zone in your BMW and need other components from the same group, such as additional sensors, control modules, or alarm system parts, check the available parts in the Other BMW category.

To compare solutions used in other brands and better understand the differences in the construction of sports variants, it is worth reading an article discussing the design and equipment of high-performance models – especially in the context of the engine, brakes, and chassis. More information can be found in the material: Audi RS vs other models – what is hidden under the hood and chassis?.