What is that module on the roof of my BMW 525i (E39)?

As far as I can tell, it doesn't appear to have any function. Does anyone know what it is?

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5 Answers

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  • 3 months ago
    Favorite Answer

    It's actually the alarm system motion sensor.

    • Ryan3 months agoReport

      Thanks! I looked it up and you are correct. 

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  • 3 months ago

    It's the d-bag sensor.

    If it doesn't sense a d-bag in the driver's seat, it won't allow the car to be put into gear.

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  • Anonymous
    3 months ago

    Time to check the owner's manual.  Could be a cabin temp sensor.

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  • 3 months ago

    It could be a temperature sensor for climate control, ultrasonic sensor for the security system, a microphone for either hands-free or automatic volume control on the audio system, or even an air quality sensor...

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  • Bill
    Lv 7
    3 months ago

    The smoke alarm.

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