Help - Alarm keeps going off

Since a month or so ago my car alarm keeps going off at the slihtest. wind, anyone going past and lately it just goes off on a calm day with nobody near it. Is there anything i can check?

I've checked for any rats or anything lol but nothing. Im having to lock the car by turning the key in the door and not the central locking because that arms the alarm. Its an E39 BMW.

Try disabling the interior motion sensor, if that doesn't work the E39 BM has a known fault with its bonnet switch (disconnect it or replace it)

I have an X5, but picked this up from BMW Land.


"Early E39s had an interior sensor that worked by microwaves, these are susceptible to radio interference from other alarms, radar detectors, Garage door openers, etc...

Try pushing the lock button on the key twice when locking the car. this will arm the system but excludes the interior sensor and the tilt sensor. BMW has a retrofit kit to a more dependable ultrasonic sensor that doesn't set false alarms. I don't know if your car has the older style sensor or not. The sensor is mounted in the center of the ceiling under a cover, if the cover has vents in it, you have the new style ultrasonic (good)sensor; if the cover does not have vents, then you have the old style microwave (bad) sensor."

Will go have a look at the sensor in 10 minutes.

The Dentist said:

Will go have a look at the sensor in 10 minutes.

Click to expand...

And three days later he is still there, I hope you are ok The Dentist.

LOL i only just managed to check it today actually. Its the vented one. I double pressed it this time and its not gone off...touch wood!!

Last time it went off at 2am, didnt know it was my car and i was cursing at the barsteward whos car it is thinking it was someone elses. only to realise at 5am that it was mine!

bet theres a wee spider crawling over the sensor

There is something in there lol. I done the double click and it was fine and then tonight i did a single click and within 2 minutes the alarm went off!