I have only had my 09 WRX for 3 weeks - the Car is Awesome - but the Alarm is seriously mental and Subaru Tech cannot diagnose the problem. The siren sounds at all hours of day (i am now getting threats of egging my car from neighbours!) and even while i am driving the siren will start yet engine keeps going. So its not the alarm/immobiliser but its the siren itself. Anyone heard of this or know what the trigger might be? Subaru Tech Australia say nothing could be wrong, the new 09 system is Bullet Proof.
I would have them at least disconnect the siren and order a new control module for it. It's not really diagnosable within the computer electronics. Plus, being that it's not immobilizing the vehicle when it goes off, I'd say it was a computer issue. Not a wiring issue. We all own computers. When was the last time you could actually call a computer "bulletproof" (I mean failure proof, not literally. . . just to save from smart comments.)
Thank everyone - left my WRX with a Subaru Tech guy who has gone above and beyond to fix it - sleeping with it in the garage!!! They wanted to be the first to diagnose the problem-seeing as it was first 09 to have it. Turns out the 'connector' wiring for the alarm was not clamped properly, so he soldered it on and he's sleeping with my WRX again tonight to check its a fix. Fingers crossed cos i want my car back!