Any reason why my car alarm keeps going off by it's self at ungodly hours of the night? This is the third time it's happened and again, expecting people to be outside leaving it on bricks. There's no one around. To be sure I've gone through the home CCTV, not a sausage.

 

No other cars around, no lorries passing, no one near it. I've checked the battery and cleaned any sensors inside I could find to make sure no creepy-crawly's where setting up home in them. But still it goes off now and then.

if you have access to VCDS you can scan the alarm module and it will tell you why it went off.

I don't no :(

But know someone who might have VCDS local to me...

Have this problem on my superb , eventually traced to the interior sensors. dont suppose you have a air freshner dangling from anywhere ? I reckon ours was moving due to the infamous door seals allowing a slight breeze in and tripping the alarm. Still goes off a couple of times a year but doesnt log any reason for it on VCDS

I do have an air freshener hanging from the mirror! Might move that some where else...

My Octavia does this too, but only rarely.....maybe once every six months or so. 

 

I've never really got to the bottom of it.....I used to think it was a trapped insect, however every time it has happened I reset the alarm and it never happens again for months which doesn't support the trapped insect theory. I don't remember any stored codes in VCDS, but I've never scanned the alarm module. 

 

I think you can adjust the sensitivity of the interior movement sensors with VCDS. Reducing the sensitivity might help, but I've not tried this. I've also heard that a failing alarm siren might cause these type of symptoms too.....they only have a life of 6 years....mine is 8 years old so is on borrowed time.  

It's frightened of the dark, leave a light on   

I've had this in two different cars and in both cases it was moths trapped in the car, coming out of hiding to flap around the interior at a certain time each night!

If you are able to get your car scanned with VCDS you can check the last 4 alarm activation causes by checking measuring block group 20 in the central convenience module. The triggers are shown as numbers and if you hover your mouse pointer over them, VCDS will display an explanation as to what they refer to. If it is the interior monitoring sensor that is triggering the alarm, you can adjust / reduce the sensitivity via the Adaptation function under Advanced Functions of the central convenience module.

The above check is what I did on my pre-fl mk2 and it revealed that in my case it was the alarm siren module that was at fault - the backup battery in the siren had leaked.

It's a spider ! Guarantee it haha

My car did this from new - over the first 5 nights the alarm went off 3 times. I took the car in and had the sensitivity of the alrm lowered.

Not had any repeats since.

I had a moth in mine once! Kept going of at night until I removed it.

Had a butterfly once as well. Kept going off at work during the day.

My old Passat did this and it was caused by water ingress into the front passenger footwell. Might be worth checking the carpets to see if they're damp.

I hope you sort it soon as it drove me up the bloody wall until I realised what was causing it!

As a temporary fix, hit the lock button on the remote twice.  It disables any faulty intrusion alerts.

As a temporary fix, hit the lock button on the remote twice.  It disables any faulty intrusion alerts.

 

This I never knew. Will give that a try.

There is also a button on the B pillar to disable the interior sensors........press it before you get out to enable this feature. 

Further to the above, when you lock your car (using a single click of the remote only), does the drivers door red led keep flashing or flash initially and then stay constantly lit? If it stays constantly lit there is a fault somewhere in the system.