Just bought an MY05 STI UK. Everything is great apart from the alarm seems to trigger for no apparent reason. It seems to be the ultrasonics because it is ok if it is armed with this off. There is nothing which can move in the car and I have the air vents closed so I dont know what is setting it off. Any advice appreciated.

Del

 

Look for insects, might sound funny but I've had this problem before, turned out there was a mahoosive spider living in my car that kept activating the ultra-sonics..

 

Park it elsewhere to test - my neighbours have a wireless doorbell which triggers mine for some odd reason. I asked them to change frequency - all fine now.

 

As above check for spiders, flies and fluff on the sensors. May seem daft but my alarm kept on going off, finally found I had left some duster fluff on the sensor! after a sunday valet.