Car alarm randomly goes off only in one location

jules0621

My friend has a new Citroen C3 Airspace and since she's had it (July 2021) the car alarm has randomly gone off at least 5-8 times a week during both daylight and night-time hours - BUT it only goes off when parked outside her house. When it goes off, no person or animal is around the car and there is no sign of tampering. Citroen have had it in 3 times and have now washed their hands of it - if their computer says no fault then there's no fault!! But as soon as the car returns to her road it starts going off. If someone were trying to steal the car then surely they would have given up after over 40 failed attempts. So I wondered if anyone has any thoughts on what could be setting a car alarm off in just one particular location. When it is parked outside my house or anywhere else it has not gone off....is it possible that some kind of electrical interference occurs in some locations and sets it off?? She is absolutely desperate for ideas at this stage since Citroen have given up on it. Thank-you.

neilmcl

Park a bit further down the road and see if it still does it. It may be that the ground the car is usually parked on isn't particularly stable or has some void under it that allows the vibrations of passing vehicles to set the alarm off. Get your friend to point a wifi camera at the car to monitor it so when the alarm goes off they can see if anything was near it.

I've never heard of electrical interference setting car alarms off. 

facade

When the alarm on my RAV4 kept going off at random on the drive I found that disabling the internal ultrasonic sensors cured it.

I think the Citroen is similar, and you can disable the internal sensor- it has to be each time you get out of the car though.

Worth trying to see if it helps.

I think my problem was air currents caused either by the wind blowing through the vents somehow, or sunshine heating the interior.

jules0621

Thank you both for your suggestions - very much appreciated. She has already had the internal sensors turned off by the garage and this made no difference unfortunately. I will suggest parking in a different place and the Wifi camera and see what that produces - although she has had lease cars with alarms while this was being checked over by Citroen and none of those went off - but perhaps this alarm has a particular sensitivity. Thank-you again.

Herzlos

What's it like where she's parked - Main road? High traffic? Bus route? Is it being set off by vibration of something big passing by

What if she parks it facing the other way? I wonder if it's only going wrong at a particular angle due to a dodgy tilt sensor.

jules0621

Thank-you Herzlos - it's parked on a fairly busy road but not a bus route. She's watched a waste removal truck going past which didn't set it off. Also it's gone off in the early hours when the road is really quiet. I will suggest parking the other way road to see if that helps. She did park on the kerb but recently tried on the flat and it made no difference to the alarm. Thank-you again for your thoughts - we'll try parking the other way round.

BOWFER

Neighbourhood cat jumping on it?
Windy street?
People bumping it as they cross the road?
The alarm switch being activated by 'something' making the car move won't show up as a fault, as it's behaving as it should (although too readily).
Maybe a new alarm switch is needed, it's just become too sensitive rather than 'faulty'.

jules0621

Thanks Bowfer. She's had myself and also another couple of neighbours really push the car and try to open doors and yet it doesn't go off then - the car has visibly moved when we've pushed and yet nothing from the alarm. But yes it definitely is very sensitive to something there - perhaps the camera will pick up something when she can set it up. Thank-you for your thoughts, I really appreciate them.

Herzlos

What's the weather like when it goes off? If it's always raining or damp then maybe there's a short.

You seem to be making pretty good progress at ruling stuff out though so I'm sure you'll figure it out eventually!

mobileron

Any radio hams taxi companys,look for big aerial on roof.

jules0621

Ah thank-you mobileron, I'll ask her to check out.