By YOUCANIC on May 21, 2019
A common problem BMW owners may face is the car alarm going off at random times. The alarm will often get triggered when the car is parked and there is no one in or by the car.
In this guide, we go over some of the most common problems that cause BMW alarm to go off or for no apparent reason. The most common solution that will fix this problem is to replace BMW hood switch.
This problem can affect BMW 1, 3, 5, 7, X1, X3, X5 and other series.
If your BMW alarm keeps going off the problem is often caused by a stuck or defective BMW hood switch but it may also be caused by any of the following.
If you are getting a hood open warning message on the dashboard or your BMW alarm goes off randomly the most likely cause is a defective BMW hood switch.
Another common location for BMW hood switch (bonnet switch or sensor) is near the driver's side strut tower.
To fix alarm going off you may need to replace BMW hood switch.
This video shows you how to replace BMW hood switch.
Disable Sensor at Locking: When locking the car using your key fob, press the lock button (BMW logo) twice. This should disable the input from the hood sensor and other external sensors. Note that this may make it easier for someone to break into your BMW.
Disconnect the sensor: Disconnect the sensor or placing tape on top of the hood sensor will prevent BMW alarm from going off randomly but is not recommended the solution.
Warning - By disconnecting or disabling BMW alarm sensors the alarm system will not go off if someone tries to open the hood when the vehicle is locked.
Some BMWs are equipped with interior motion sensors that detect motion inside the car. There is also a tilt sensor that monitors the movement of the vehicle. The tilt sensor purpose is to detect thieves who may try to steal the car, steal your wheels or tow the car away without permission.
The interior sensors may not work properly in situations when the car is parked in congested garages. It may detect movement outside the car. It also may not work properly if the windows are open.
The interior sensor on BMW can be disabled by following this procedure.
Lock vehicle using keyfob remote. > Within 10 seconds press the lock button again. > Lights will flash. This will turn off the tilt alarm sensor and interior motion sensor.
An older car battery can trigger the alarm to go off as well. If the battery voltage drops below 9 volts the alarm may go off randomly. Battery voltage can drop for two main reasons:
If your BMW battery is over seven years old, it may be time to change it anyways.
Follow this guide on how to change a BMW battery yourself.
If you have replaced the hood switch and the battery and your alarm will still go off, further troubleshooting is necessary. Complete a full system scan using a BMW scanner and examine the fault codes present.
Diagnosing BMW problems with Foxwell for BMW scanner. There are many scanners that are capable of reading and clearing BMW fault codes.
We hope that you found this guide on how to troubleshoot BMW alarm going off randomly helpful. If you have any comments or would like to report an alternative solution use the comment section below.