Car alarm going off randomly

passremarkable

Hi,
Have Audi A3 2009. Alarm went off 4 times last night randomly , lights flashing and siren going off. Had to get up and unlock to turn it off. This happpened about a week ago and hasn’t happened in about 2 years before that.Car hasn’t been driven in 3/4 weeks if that makes a difference. Just seems so random. Only seems to happen at night.
Anyone any ideas ?
PM

KevinCavan

passremarkable wrote: »

Hi,
Have Audi A3 2009. Alarm went off 4 times last night randomly , lights flashing and siren going off. Had to get up and unlock to turn it off. This happpened about a week ago and hasn’t happened in about 2 years before that.Car hasn’t been driven in 3/4 weeks if that makes a difference. Just seems so random. Only seems to happen at night.
Anyone any ideas ?
PM

Somebody’s waiting for you to turn off the alarm, so that they can whisk it away.

B-D-P--

Low battery,

That sometimes triggers the alarm

denismc

Spiders or flys. I have a skoda and the alarm is very sensitive, if there are spiders moving around in the car they can set off the alarm.
Or low battery

lalababa

Low battery most likely culprit , as a car gets older the electric Gremlins like to act up when the battery gets low.

Wetbench4

My car alarm goes off if i leave my phone in the car or when my car battery is low. Have you any tablets or phones left in the car or dashcam with wifi? Might be the cause.

Visconti

Spiders and flies or sometimes a gush of wind if the vents are open. Sometimes a solder joint on one of the sensors making breaking contact.

passremarkable

Thanks for replies. Il get battery checked.
May be if I take it for a spin would that help things?

PickYourName

Did you happen to leave a Bluetooth enabled device in the car by any chance? I had a long-standing problem with a Toyota Prius I had. Periodically, the alarm would go off all by itself for no reason. It had me demented. I spent a lot of time on the Internet trying to find the source. One suggestion (several were along the lines of those already mentioned), was leaving a Bluetooth enabled device in the car could set off the alarm. No, I thought, that couldn’t possibly make any sense (I’m an engineer by training, and I’ve worked with low-power radio comms and everything I know says it doesn’t make sense). Anyway, it turned out that every time the alarm went off and I checked, I found my daughter’s iPod in the car: once removed, it didn’t happen again. It still makes no sense to me, but worth a try I would have thought…...

passremarkable

PickYourName wrote: »

Did you happen to leave a Bluetooth enabled device in the car by any chance? I had a long-standing problem with a Toyota Prius I had. Periodically, the alarm would go off all by itself for no reason. It had me demented. I spent a lot of time on the Internet trying to find the source. One suggestion (several were along the lines of those already mentioned), was leaving a Bluetooth enabled device in the car could set off the alarm. No, I thought, that couldn’t possibly make any sense (I’m an engineer by training, and I’ve worked with low-power radio comms and everything I know says it doesn’t make sense). Anyway, it turned out that every time the alarm went off and I checked, I found my daughter’s iPod in the car: once removed, it didn’t happen again. It still makes no sense to me, but worth a try I would have thought…...

No don’t have any devices at all.
Hasn’t gone off since.
So fingers crossed.

quenching

PickYourName wrote: »

Did you happen to leave a Bluetooth enabled device in the car by any chance? I had a long-standing problem with a Toyota Prius I had. Periodically, the alarm would go off all by itself for no reason. It had me demented. I spent a lot of time on the Internet trying to find the source. One suggestion (several were along the lines of those already mentioned), was leaving a Bluetooth enabled device in the car could set off the alarm. No, I thought, that couldn’t possibly make any sense (I’m an engineer by training, and I’ve worked with low-power radio comms and everything I know says it doesn’t make sense). Anyway, it turned out that every time the alarm went off and I checked, I found my daughter’s iPod in the car: once removed, it didn’t happen again. It still makes no sense to me, but worth a try I would have thought…...

I had a 2005 Prius with the same "problem", the alarm would go off every time I left a phone in the car. Tried it in a friends Prius and theirs was the same. The same devices in other cars were fine!

ianobrien

OP, this may sound daft but have you the heater set to draw in fresh air or to recirculate the air? Set it to recirculate. We had it before that a car alarm would go off at random times. It stopped when we set the heater to recirculate. The problem was that there was the odd gust of wind that would make its way through the heater into the car that would set off the alarm. Blocking it off via changing it to recirculate when leaving stopped the alarm

passremarkable

ianobrien wrote: »

OP, this may sound daft but have you the heater set to draw in fresh air or to recirculate the air? Set it to recirculate. We had it before that a car alarm would go off at random times. It stopped when we set the heater to recirculate. The problem was that there was the odd gust of wind that would make its way through the heater into the car that would set off the alarm. Blocking it off via changing it to recirculate when leaving stopped the alarm

Yea I can try it next time it happens.
Seems to be ok at the moment.
Hadnt been driven for a number of weeks so just went out and turned on engine for a few minutes.
Cheers though

TheRiverman

An older battery that might be still fine for starting the engine can still cause electrics to fail.I had a Renault Megane for five years,one day the power steering failed.I thought I was facing a big bill as the power assist on the Megane is electric as opposed to hydraulic on other cars.I checked with a mechanic and online and decided to change the battery instead of replacing the power assist unit.It worked as the power steering never failed again over the following two years that I had the car and as far as I know the person who now owns the car hasn't had any problem with it either