I thought I would share the cause of my fault on my 2011 TDV8. My alarm would go off sporadically for no reason. It got progressively worse until it drained the battery. I had to leave the car unlocked until I found the fault. I replaced the battery, which seemed to improve the situation, but the alarm still went off after a few hours. It turned out to be a bad connection at the motion/volumetric sensor in the middle of the roof. This showed up when scanning the codes with an icarsoft diagnostic tool. I unplugged the unit and reconnected. It has been fine since. I hope this helps anyone with a similar fault.