Hi,

I have a 72 plate Ford Focus. About four weeks ago the alarm went off at like 8pm I stopped it with the key and thought nothing off it. Then it randomly kept going off every few days and was getting harder to stop. I took it to a garage who said no error codes and battery fine. I started putting it on a reduced guard and it seemed to stop it. Then it went off sparodically through the day. The car wasn’t even locked and I couldn’t get it to stop. Other times it was stopping itself before I had chance to even grab keys. Another mechanic had a look and changed the car battery and showed me the diagnostic thing which had no errors and all the door sensors seemed to be working fine.

Two days later it was going for half an hour last night. Turning the ignition on does not stop it. All my neighbours were out last night I’m at the end of my tether.

Please can anyone help 🙏😭

Bonnet latch switch

If it's going off when not locked then it's not any of the usual switches.

Ford stopped fitting the rain tray above the alarm sounder around 2021. I wouldn't be surprised if your sounder is damp or corroded, or it's internal backup battery is failing. It's hidden under the 'binbag' next to the passenger side front wing under the bonnet.

It’s not the bonnet latch as it’s not the full alarm sounding it’s more siren noise? Plus the mechanic run full diagnostic and all the sensors seemed to be working as. He’s coming back today to look at the silly little back up battery thing.

It’s mortifying my poor neighbours are all OAPs and I I’ve spoken to them all and explained. It doesn’t even go off when the ignition is running. I’m at a loss

I've read before this can be a symptom of a flat backup battery or corroded connectors. If your desperate and it's nothing but a nuisance if it were mine (in the short term at least) I would get to the alarm unit/sounder and disconnect the sounder inside it, snip it's wire/unsolder it etc that way the car will just flash its indicators and not make a noise. I'm guessing just disconnecting the unit completely would just throw fault codes/error messages so I would make it mute!

So update the mechanic has removed the back up battery sounder thingy! Sorry I don’t know the correct terms 😂

myself and my neighbours had a blissful sleep last night so I’m really hoping this is the end of the saga!

Thank you for all the advice