Alarm goes off randomly

  • Thread starter Thread starter mjt
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mjt

mjt

mjt

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<3 old BMWs!

So yeah, the alarm seems to have a mind of its own these days and goes off every now and again for fun.
It did it three times today, within minutes of locking the car.

Is this a sign of a low battery?
It's a Z3 Coupe with a stock factory-fitted BMW alarm.
 
Could be the bonnet sensor. My e46 did this in hot weather. The bonnet would expand and lift high enough to release the switch.

If it is, there are two possible solutions:
1. Tape down the switch so it's always closed (means the alarm wont activate on the bonnet)
2. Place a rubber grommet (BMW actually sell the part - made by 3M tho) on the underside of the bonnet where it pushes down on the switch.

HTH.
 
Just locked the car while holding down the sensor, then let go and nothing happened..

Perhaps it's faulty, rather than the bonnet lifting off?
 
Plug in a BMW specific diagnostics and it will tell you if its the bonnet sensor.
 
Mines has started to do this in the heat. couldnt work out what it was

just locked mine with the bonnet sensor held and let go - the alarm sounded.

so must be the bonnet expanding!

i need to do what Joe T said and add some tape or a grommet.
 
I had a problem like this except it would go off even whilst driving the car.

And it would be all distorted, the volume would vary as would the pitch and tune lol!

Had to replace the siren speaker thingy.

Not a E46 btw, or any BMW for that matter.
 
mjt said:
Just locked the car while holding down the sensor, then let go and nothing happened..

Perhaps it's faulty, rather than the bonnet lifting off?
Click to expand...

Wait a while. My car doesn't arm the alarm for 20 seconds after you lock it, and I'm pretty sure other cars are similar
 
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