Since Monday I've had problems with my car alarm on my 05 Sti going off on it's own, It's happened 3 times now at different times, on different days, luckily not night time.

Its' odd because the indicators don't flash when it goes off like they do when you turn on/off the alarm. Although they did flash 5 times I think the first time and repeatedly after work today!

I'm worried because I can start the car with the alarm on, I've tried all sorts like holding the button to turn it off, opening/closing doors an windows, blowing dust off the sensors on the A-Pillars turning the key to different points in the barrel, It make no sense....But I can hear a buzzing under the bonnet when it goes off on its own, Is it goosed?

Recommendations please apart from get a new alarm which I'm gonna do if the problem persists.

 

try battery back up ..the one in the alarm itself, maybe located under windscreen wipers

 

Mine started going off by itself randomly, but I also had signal interference with immobiliser/locking car. Eventually after few months of issues I got a new cat1 alarm and it's been good as gold since. Hope you get it sorted mate