My bmw car alarm keeps going off?

I had the same problem with my 2000 X reg 320Ci conv. It turned out to be the bonnet (hood) sensor switch. I took it apart, give it a good clean replaced it and everything's been ok since. Apparently, it's another common one.

Dvd
April 2008

This is probably a known fault with convertibles its the interior sensors that are faulty and trigger the alarm sporadically. your local agent will be able to read the alarm ecu trigger counter and verify this only action is to replace for later versions.
You can allso disable interior sensors by pressing "lock" button twice when locking vehicle (may invalidate insurance etc as sensors are there for a reason) this allso turns off the tilt sensor if fitted so if someone trys stealing your wheels no alarm!
as last note large metal objects set the sensors of ie garage door if parked close by.

ian.
September 2007