Alarm going off randomly

[Cuprat]

Hi all

I’ve not had the car too long and as far as I’m aware this wasn’t pre-existing issue (though could have been)

Yesterday the car alarm went off for no reason at 13:30 and then again at 22:30. I left the car unlocked after that so no further issues

Bit of additional info;

It has been raining heavily for the last 24 hours - there is no damp in the car that I can see (foot wells or boot)

I had a new battery fit 3 weeks ago - seems to have been coded ok as everything is working fine

I’ve not used the car for a week - last journey was a 90 minute drive

No lightswould appear to be on in the car. The Centre arm rest has been fixed with magnets due to a broken latch. These had come loose so I’ve had to re-attach. The arm test was still shut though so it hadn’t popped fully open to trigger the alarm

I’ve had a recent starting issue - not failed to start but a slow turn over a couple of times

I’ll try and get it booked in but any ideas on what it could be. From looking on here and google it seems to be it could be;

Bonnet latch - I’ve not opened the bonnet recently but could the rain have moved it slightly?

Battery - new battery but could be a dud or not holding charge due to another issue

Damp - I think the car looks ok

Anything else?

Thanks

 

[Chippie]

There’s a sensor for the alarm in the drivers door that can set off the alarm during heavy rain, I’ve had this a few times over the couple of years I’ve owned it, apparently the BMW fix is the place some aluminium foil over it.

 

[Cuprat]

Thanks for that. I hadn’t come across that one!

 

[Timmyboybunter]

There’s a sensor for the alarm in the drivers door that can set off the alarm during heavy rain, I’ve had this a few times over the couple of years I’ve owned it, apparently the BMW fix is the place some aluminium foil over it.

Me too - just once in 20 months, during an especially heavy shower.

 

[flybobbie]

Don't put anything with steel behind seats, i placed a small scissor jack, the alarm went off so removed it.
Aluminium fire extinguisher ok though.

 

[Cuprat]

Thanks all.

Car booked in for tomorrow

Out of interest - where is the bonnet sensor located? I’ve looked and can’t see anything obvious so wonder if it has been removed previously?

Thanks

 

[Cuprat]

Thanks all.

Car booked in for tomorrow

Out of interest - where is the bonnet sensor located? I’ve looked and can’t see anything obvious so wonder if it has been removed previously?

Thanks

 

[flybobbie]

https://www.realoem.com/bmw/enUS/showparts?id=LM32-EUR-05-2009-E89-BMW-Z4_23i&diagId=41_1887
Item 3.

 

[Cuprat]

Thanks. So I’m assuming it’s this?

 

[Cuprat]

There’s a sensor for the alarm in the drivers door that can set off the alarm during heavy rain, I’ve had this a few times over the couple of years I’ve owned it, apparently the BMW fix is the place some aluminium foil over it.

Me too - just once in 20 months, during an especially heavy shower.

After diagnosis this appears to be the issue

Apparently the part needed to fix it is on back order and there is no eta for it

Any idea how to lock the car without setting the alarm?

I was leaving it unlocked but that’s not ideal

 

[Cuprat]

There’s a sensor for the alarm in the drivers door that can set off the alarm during heavy rain, I’ve had this a few times over the couple of years I’ve owned it, apparently the BMW fix is the place some aluminium foil over it.

Me too - just once in 20 months, during an especially heavy shower.

After diagnosis this appears to be the issue

Apparently the part needed to fix it is on back order and there is no eta for it

Any idea how to lock the car without setting the alarm?

I was leaving it unlocked but that’s not ideal

 

[ianl]

The part needed is just a piece of foil according to many BMW garages BMW have produced a specially shaped version which sticks on. Attached are the instructions they will follow to install it (needs to be done in both doors). I’ve done this on mine. I am going to do it again though as it still goes off in torrential downpours, so I’m going to try two layers of foil. It is much better than it was though.

I’ve not heard the bonnet sensor being the cause of this on an E89. This can be a cause on the E85, which is why it might appear on Google searches.

To still lock the car, without the alarm, do this:
1. Get out of the drivers side and close the door.
2. Get into the passenger side and close the passenger door.
3. Press the “lock the doors” button in the centre of the console.
4. Get out of the passenger door.
5. Push down the door lock knob on the passenger door and close the door.
6. It should now be locked and the alarm will not be on.

I’ve done this from memory so hopefully it is right.

 

[Chippie]

ianl
Thanks for sharing

 

[Cuprat]

Thanks Ianl

The way to not set the alarm does seem to work so handy to know. My neighbours say thanks

Car has had the fix of the 2 door sensor things. So far seems ok but we have not had really heavy rain yet

 

[ronk]

Thanks Ianl

The way to not set the alarm does seem to work so handy to know. My neighbours say thanks

Car has had the fix of the 2 door sensor things. So far seems ok but we have not had really heavy rain yet

The Dealer did the "Fix" on a previous E89 I owned and it was 100% successful