Like many of us with key FOB's the battery needs replacing from time to time due to usage. I am presently experiencing issues with having to be up next to the vehicle for the lock to unlock and even then it may require a couple of presses. I took the battery out and the voltage measures about 2.5 volts. At what point is loss of voltage considered to be enough to replace battery? For those who don't have a volt meter I would encourage you to get one. Easy to use and helpful in trouble shooting batteries, including the car battery. I've noticed the last couple of weeks a slight delay in the engine turning over (if you're not the daily driver you probably wouldn't notice it) and I still have the factory battery that is coming up on three years (still under warranty). I went out this morning and checked it since it's been sitting out overnight in the cooler temperature and it still shows 12.5 volts.