alarm problem

freddie 5

Registered User
Feb 7, 2011
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Gillingham. Kent
Hi guys,

I have a problem that is driving me and my neighbours mad. The alarm on my A4 keeps going off, Ive checked that all doors are shut, bonnet and boot also shut tight. But no matter what I do, the damn thing keeps going off. I think thhat the problem may be with the internal sensor that is located behind the drivers seat in the upright. Ive looked at manual and all it can advise me is how to turn it off every time you lock the car, can this be switched off perminantly?

Please help before I get my car towed by the police.

you will probaly find its the internal battery thats knackered, when they start to fail it keeps triggering the alarm

only fix is to disconnect the siren in the boot, and either fix it, by rigging up a battery pack etc, as replacement batteries arent available since they were only made by one comapny that went bust adn thats if the circuit board hasnt been eaten by the acid out of the battery

or replace the whole siren, aroun £90 from dealer but can get of ebay for much less also a6 siren fits, arragon will point you in right direction as to which ones do if you ask him
Any one near you with VCDS?
That will tell you what is setting the alarm off.

As 205man said, disconnect the siren and then set about fixing it.
As above, vagcom scan to see whats going on.

Its quite likely the backup battery as mentioned, but if not could be a dodgy door switch or similar.
Check to see if the bonnet sensor pin is snapped, mine was and kept setting my alarm off. I just disconnected the wires from it and its stopped now.
Update on this. I have checked the bonnet sensor, it appears to be ok, but a bit loose in body work. I have cleaned it up and secured it better, but Im having problems finding the horn that is located in the boot. I have taken both covers from each side of the car, the drivers side has the central locking system, the passenger side has a sealed box with Nokia written on it and nothing else. Is it located in the box? Any help would be appriciated. Thanks. I am driving an A4 Avant if that makes any difference
Lift up rear seat and you'll find control unit for interior sensors, try unplugging that
Pre facelift horn is located in left cubbyhole hole behind speaker box, you cAn get to it by removing cd changer cage
and if its a facelift, its on the right hand side of the boot, down low below the level of the floor in the boot.
latest update. found the horn and disconnected, only problem was the battery on the car drained. here is a pic of the horn, a complete and utter pain to locates. looked on here for info, all I can find is details on how to replace the battery pack, cant find anything like this in my car. Im driving a 98 plate A4 Avant. Need soem help here. Thanks


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