I got a call this morning about 9:30 that my den motion sensor had triggered my security alarm. The company dispatched police and I raced home. Everything was fine, thankfully -- I'm still coming off the stupid adrenaline. Anyway, I called the alarm company to ask if they had any insight to what happened. Two things: 1: The den motion sensor is a wireless unit, and 2: my neighbors did NOT hear the alarm go off! The tech on the phone thought the lack of audible alarm was odd and had me test the system and it seemed to be working fine (alarm sounded and everything). I asked him if low batteries in the motion detector could be to blame and he said it would give me a trouble code but not set off the alarm (I get trouble codes from the fob batteries going dead about once a year so I know all about that). I have never replaced the batts in this sensor because I have never had a trouble code calling for it. The best answer the tech had was "wait and see if it does it again." Some research has indicated that low batteries CAN cause a false alarm, but there seem to be very mixed opinions about this. Anyone have any insight? I have had this system for four plus years now and never had a single problem with it until now. Probably going to replace the batteries just on principle, BTW.