Alarm problems

Ok, I'm still having problems with my alarm. All four indicators will start flashing for no apparent reason although no siren sounds! Do I have an alarm fitted? Thought it was a standard item on all cars these days. If it's not an alarm problem, any ideas on what's causing it?
 
I've just tested it triggers by locking the car with the roof down and then putting my hand inside the car. The indicator lights all flash but no alarm siren. Hmmm, I wouldn't mind betting it's been disconnected by the previous owner because it kept going off on it's own! Why do car alarms never work properly :headbang:
 
You will probably find it's the bonnet sensor that is the real problem although as you say somebody may have disconnected the siren also.
 
is it definitely oem ?

seat occupancy sensors id say... if i wave my hand in with the roof down it does nothing, it's about pressure on the seat..
 
Pretty sure it's an oem alarm. I reckon the siren has been disconnected due to it triggering for no apparent reason. It annoys the he'll out of me when people do half arsed stuff like this rather than getting it fixed properly :thumbsdown:
 
Andy said:
is it definitely oem ?

seat occupancy sensors id say... if i wave my hand in with the roof down it does nothing, it's about pressure on the seat..

Should do something if you put you hands down toward the seat base (no need to touch though), the sensor is at the back of the transmission tunnel, and I guess the range is targeted quite tight due to potential lack of roof.
 
Is this sensor easy to replace? I guess I also need to find out why the siren isn't working. Sigh, seems to be one thing after another!
 
I have a 2004 (2.2) Z4. I too had a problem with the alarm going off randomly with no pattern to it. Fine one day, going off every 5 minutes the next. Took it to main dealer who said 9 times out of 10 it is the bonnet sensor which the most inexperienced DIYer could change in a couple of minutes. This didn't fix my alarm problem however. The next thing they check is the interior cabin sensor which turned out to be the problem with my alarm. Try this next if the bonnet sensor doesn't appear to be the cause. :roll:
 
Sorry to drag up an old thread. I'm having problems with my alarm too. I've disconnected the bonnet sensor but yet it still goes off randomly.

The alarm going off does seem to coincide with a neighbours cat sitting on the roof... surely it can't be "that" sensitive can it???

When I de-activate the motion sensor it seems to be fine though....

Does anyone know how much the new interior sensor is and how difficult it is to replace? Does it need the sensitivity adjusting or is it fixed??

Cheers in advance all.
 
I would try the bonnet sensor first as its the most likely and cheapest option. But doubt it's due to expansion as it wouldn't be that great.
 
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