Security alarm (BMW 3 Series E46)

The security alarm responds to the following actions of unauthorized persons:

• opening a door, hood or trunk lid
• movement inside the car (microwave interior protection sensor)
• change in the vehicle's tilt, for example, when attempting to steal a wheel or tow it
• battery power interruption

The system reacts differently to the above actions by outsiders depending on the vehicle version:

• an alarm sounds for 30 seconds
• the emergency light is turned on for 5 minutes*

Setting and disarming the alarm

The alarm is armed and disarmed simultaneously with the vehicle being locked and unlocked by turning the key in the lock or using a remote radio control.

The microwave interior protection sensor is activated approximately 30 seconds after the last time the key is turned in the door lock.

If the alarm system has been set correctly, this will be indicated by a single activation of the emergency light.

The trunk can also be opened after the alarm system has been set by pressing button 3 on the radio remote control (refer to Section Keys, single lock and anti-theft system). After closing the trunk lid, it is again taken under the control of the security alarm.

Some export models can only be controlled by remote radio control. Unlocking the car with the key triggers the alarm on these models. Pressing button 1 ("Unlock") or starting the engine switches off the alarm.

Indicator lamp signals

The indicator lamp is located under the rearview mirror.

The indicator lamp is constantly on: the security alarm is activated.





The indicator lamp flashes when the alarm is set: the doors, hood or trunk lid are not closed tightly. Even if you leave everything as is, the remaining properly closed objects will be taken under protection, and the lamp will start to burn constantly after 10 seconds. However, the microwave sensor for interior protection is not activated.

The control lamp goes out when the alarm is removed: no unauthorized manipulations were performed on the vehicle.

The indicator lamp flashes for approximately 10 seconds when the alarm is disarmed: a signal of outside interference.

After the alarm is triggered, the indicator lamp will again remain lit continuously.

Roll alarm sensor

To avoid an alarm signal when the tilt sensor is triggered spontaneously (for example, in a double-decker or when transported by rail) or as a result of the activation of the microwave interior protection sensor, these systems can be switched off simultaneously.

Double lock the car, i.e. arm it twice. In other words, press button 2 on the radio remote control twice or lock the car twice with the key (refer to Section Keys, single lock and anti-theft system).



The indicator light will flash briefly and then remain on continuously. The tilt sensor and the microwave interior protection sensor will be disabled until the car is disarmed.

Microwave interior protection sensor

The microwave interior protection sensor transmitter and receiver are located under the cover on the ceiling.

For the microwave sensor to function properly, the glass and hatch cover must be closed.

Turn off the microwave sensor if:

• children or animals must remain in the car,
• the windows or sunroof must remain open.

Interrupting the process of closing the sunroof and windows within the first 10 seconds and immediately resuming it will cause the tilt sensor and the microwave interior protection sensor to be switched off. If this happens, the alarm system must be switched off and then on again to switch the tilt sensor and the microwave sensor on.

The article was copied from an online resource BMWMan