Dear All,

I own a Fabia III (2015) and I’m currently experiencing an issue where the car incorrectly detects that a door is open—likely due to a faulty door sensor. While this is inconvenient, the more pressing problem is that the anti-theft alarm is being triggered randomly, sometimes during the night, which understandably is causing distress to my neighbours.

The earliest available appointment at the garage is in two weeks, and I’d like to avoid further disturbances in the meantime. I’ve been wondering whether disconnecting the car battery would disable the alarm system temporarily. Despite doing quite a bit of research, I haven’t found a clear answer.

If anyone has experience with this or can offer advice, I’d be very grateful. Apologies if this seems like a basic question, and thank you in advance for your help!

Edited 12 August, 202512 Aug by Fab3Nottingham

The alarm horn unit has its own battery, so I'd think that the only way to silence it would be to locate it and unplug and maybe remove it.

I've never checked to see what happens when the car battery is disconnected, in terms of how the alarm would react if the car was then mechanically locked.

7 hours ago, Fab3Nottingham said:

anti-theft alarm is being triggered randomly

If you push the anti alarm button on the B post, does the alarm still go off?

Thanks. AG Falco

2 hours ago, rum4mo said:

The alarm horn unit has its own battery, so I'd think that the only way to silence it would be to locate it and unplug and maybe remove it.

I've never checked to see what happens when the car battery is disconnected, in terms of how the alarm would react if the car was then mechanically locked.

Thanks very much for your reply.

Unfortunately, the battery for the alarm horn unit is located underneath the car and is essentially inaccessible without a lifting platform. My hope is that by disconnecting the main car battery—while the alarm system itself remains powered—the fault will no longer be reported, and the alarm will stay silent.

50 minutes ago, AGFalco said:

If you push the anti alarm button on the B post, does the alarm still go off?

Thanks. AG Falco

Unfortunately, the alarm button on the B-pillar only disables the motion sensors—either inside the car (e.g., if you leave your dog inside) or external movement (such as when the car is on a ferry). I'm afraid this won't resolve the issue I'm experiencing.

I've done quite a bit of research on possible solutions. Suggestions like disconnecting the siren require technical work I'm neither qualified nor keen to undertake. I also tried pulling the fuse, but that didn’t resolve the issue—presumably because of the alarm’s backup battery.

In the meantime, I’ve contacted two dealerships—one in the UK and one in Germany—and asked whether disconnecting the battery would stop the alarm. Confusingly, their answers didn’t quite align.

I’m still hoping that someone in this forum may have actually tried this and can shed more light on the issue. It would be a huge help to mechanically clueless car owners like myself who end up battling with electronics that seem to have a mind of their own.

8 hours ago, Fab3Nottingham said:

Dear All,

I own a Fabia III (2015) and I’m currently experiencing an issue where the car incorrectly detects that a door is open—likely due to a faulty door sensor. While this is inconvenient, the more pressing problem is that the anti-theft alarm is being triggered randomly, sometimes during the night, which understandably is causing distress to my neighbours.

The earliest available appointment at the garage is in two weeks, and I’d like to avoid further disturbances in the meantime. I’ve been wondering whether disconnecting the car battery would disable the alarm system temporarily. Despite doing quite a bit of research, I haven’t found a clear answer.

If anyone has experience with this or can offer advice, I’d be very grateful. Apologies if this seems like a basic question, and thank you in advance for your help!

The faulty door sensor could well be the cause of the alarm being triggered. as mentioned before, the alarm has its own, integrated, battery, disconnecting the vehicle battery will not disable the alarm.

I strongly suspect that the alarm operation will be 'Fail Secure' and will sound if the battery is disconnected while the alarm is armed.

53 minutes ago, Warrior193 said:

The faulty door sensor could well be the cause of the alarm being triggered. as mentioned before, the alarm has its own, integrated, battery, disconnecting the vehicle battery will not disable the alarm.

I’m fairly certain the sensor is the culprit, as the “door open” alerts and the random car-theft alarms started occurring around the same time. That said, I suppose I’ll only know for sure once a dealer has had a proper look and run diagnostics on the car (in two weeks at the latest, I hope)

44 minutes ago, Warrior193 said:

I strongly suspect that the alarm operation will be 'Fail Secure' and will sound if the battery is disconnected while the alarm is armed.

I also have a few suspicions whether it might or might not work, but I’m still hoping someone here can share their experience. It would be great to hear from someone who’s tried it firsthand.

If you pull the fuse (#17) for the alarm horn, at least any time it subsequently goes off, if it does at all, will deplete the internal battery until it's empty.

Indicators may still flash if alarm is triggered, but that's a bit less antisocial.

Edited 12 August, 202512 Aug by Breezy_Pete
added fuse number

10 minutes ago, Breezy_Pete said:

If you pull the fuse (#17) for the alarm horn, at least any time it subsequently goes off, if it does at all, will deplete the internal battery until it's empty.

Indicators may still flash if alarm is triggered, but that's a bit less antisocial.

I’ve already pulled the fuse, but the alarm horn remained completely unfazed. I’m afraid its internal battery will only run out of energy after my neighbours have run out of patience. :-)

I don't see that disconnecting the vehicle battery can make matters any worse then; so worth trying?

I'd remove the thing for you tomorrow if you were a lot closer.

13 minutes ago, Breezy_Pete said:

I don't see that disconnecting the vehicle battery can make matters any worse then; so worth trying?

I'd remove the thing for you tomorrow if you were a lot closer.

Thanks so much for the offer—I really appreciate it. Disconnecting the battery itself wouldn’t be a problem for me if I decide to go down that route. I’ve done it before and feel confident doing it again.

The reason I’m seeking a bit of reassurance before actually going ahead is that I have other plans over the next few weeks, and if this “solution” doesn’t work (i.e., the alarm still gets triggered), it could cause some complications down the line.

I’d rather not go into the details publicly, but if you're curious, I’d be happy to share more via private message.

@Everyone: I really appreciate all your comments and suggestions. As a newbie to this forum, it’s great to feel so welcome—thank you!

Daft question - is the horn(s) accessible at all?

I just wonder if you can stuff a rag in/over it until the battery runs out. It won't silence it, but should help.

FYI - you'll be able to disable interior monitoring and/or the towing away alarm, but I doubt this can be disabled.

I would just remove the battery, put up with it for a bit (can't be more than 30 minutes, surely) and let the thing die completely. I would lock all of the doors with the key, then open the drivers door manually with the key and open the bonnet. If everything dies with the car unlocked, you are only usually able to lock/unlock the drivers door with the key. If it's completely dead, you won't be able to lock the boot/other doors.

Even if you were to get an OBD scanner to see the fault, and it was the sensor, you wouldn't be able to fix it would you? The only option sounds like securing the car, dead, and taking it to the dealer in two weeks.

Now I'm curious...........

Edited 12 August, 202512 Aug by OccyVRS

8 minutes ago, OccyVRS said:

Daft question - is the horn(s) accessible at all?

I just wonder if you can stuff a rag in/over it until the battery runs out. It won't silence it, but should help.

FYI - you'll be able to disable interior monitoring and/or the towing away alarm, but I doubt this can be disabled.

I would just remove the battery, put up with it for a bit (can't be more than 30 minutes, surely) and let the thing die completely. I would lock all of the doors with the key, then open the drivers door manually with the key and open the bonnet. If everything dies with the car unlocked, you are only usually able to lock/unlock the drivers door with the key. If it's completely dead, you won't be able to lock the boot/other doors.

Even if you were to get an OBD scanner to see the fault, and it was the sensor, you wouldn't be able to fix it would you? The only option sounds like securing the car, dead, and taking it to the dealer in two weeks.

Now I'm curious...........

I really liked your suggestion with the rag—very creative! Unfortunately, it won’t work with my plans over the next few weeks, but I hadn’t come across anything like it during my earlier research, so thanks for sharing it.

I’m aware of many of the alternative approaches discussed in this and other forums, which have been incredibly informative. That said, to keep this thread focused, I’d prefer not to revisit those broader discussions here.

Ideally, I’m just looking to hear from someone who has actually disconnected the battery and can confirm whether the alarm did—or didn’t—go off randomly afterwards.

Thanks again to everyone for the helpful input so far!

If you can get a rag in the alarm horn you might, or might not, also be able to disconnect the horn perhaps. Does this still leave bleeps that need programming out through the infotainment menus(?), does it bleep with alarm going off(?).

Have you anywhere secure where you could leave the car unlocked.

Could you take your car somewhere where the noise of the alarm wouldn't annoy anyone except you and if you really want to find out for yourself try disconnecting the car's 12v battery, or disconnect the offending sensor perhaps. VWŠkoda does seem to have very thin fragile wiring and a ridiculous amount of different fragile wunderbar fantastic-plastic wiring connectors ("Simply Clever"?).

You could look and see if there's a Briskoda member near you with a VCDS scan tool program that may be able to help you in some way, (though it might be as you say a faulty sensor, or connection or wiring or water got in). - https://www.briskoda.net/forums/topic/262215-list-of-vcds-owners-previously-known-as-vag-com-vcp-owners/#comment-3091029

Edited 13 August, 202513 Aug by nta16
missing word

The alarm is a siren with a battery. Nothing to do with the horns. Unless different with a MK3. Is it not below the windscreen scuttle?

This thread suggests that is where it's located: Car alarm keeps sounding - Skoda Fabia Mk3 (2014-2021) - BRISKODA

Edited 13 August, 202513 Aug by Breezy_Pete

8 minutes ago, Ootohere said:

The alarm is a siren with a battery. Nothing to do with the horns. Unless different with a MK3. Is it not below the windscreen scuttle?

Bad wording, following horn instead of siren, we call it the alarm horn, and yes I thought from previous threads posts here when a member put he got a s/h alarm siren/horn battery is was near the windscreen.

ETA: beaten to it again

Edited 13 August, 202513 Aug by nta16
ETA:

Guys I really appreciate your advice and recommendations but there are already several discussions of these alternative solutions on this board, so let’s go through them again.

I am really just looking for someone who’s able to help answering my initial question.

IMO,

If it needs a new Siren & Battery buy one, & fit it. If you can not change the battery yourself.

If you can not diagnose what the fault is go to a Auto Electrician not a Main Dealership.

20 hours ago, Fab3Nottingham said:

Thanks again to everyone for the helpful input so far!

There is another way:

Open the car.

Open the boot.

Get in the car and shut all the doors but not the boot.

Push the car door lock button on the dash.

Get out of the car via the boot.

Close the boot.

This locks the car, but wont turn the alarm on.

Thanks. AG Falco