Same thing happened to mine and there were alot of replies on here regarding this but noone seemed to have a clear cut answer, so I ended up pulling the fuse. Its a pain to manually lock the door but weighing the alarm to the manual locking its a choice I chose. Lots of ppl said to replaace the key fob batteries, that didnt work, some suggested changing the car battery but mine tested good so I wasnt about to replace that, some ppl said there may be water in the sensor area which was located under the carpet in the trunk which I tried and was pretty much causing more problems than fixing it. So, thats when I decided to pull the number 9 fuse. Look in your book. But that was my experience. Maybe this thread will come up with another solution. Good Luck I know how annoying it can be.