Many modern cars come with a remote locking system that comes as a key fob, or remote transmitter, that you can attach to your key ring. The key fob has buttons that allow you to lock or unlock all of your doors, open the boot or hatch door, or activate a panic alarm which sounds the vehicle horn on and off. The key fob is powered by a small battery that over time will weaken, which will shorten the operating distance that you have become accustomed to when using your remote. Changing the battery in your remote transmitter will restore it to its former usefulness.
Remove the remote transmitter from the key ring to better access the battery cover.
Remove the rear battery cover by inserting the edge of a coin into the slot at the end of the key fob. Turn the coin slightly to separate the battery cover from the remote transmitter. Set the cover aside. For some key fobs you will need a small screwdriver to take the two parts of the fob apart.
Remove the battery from the transmitter by prying it up with the edge of a fingernail. Do not use a metal tool to pry the battery out or you could damage the electronic components of the transmitter.
Install the new battery, putting it in the battery compartment in the same orientation as the old battery. Check the inside of the battery cover for specific instructions regarding your remote transmitter.
Position the battery cover back onto the key fob and press the two halves together until they snap into place. Tighten the screw, if your fob has one.
Check the operation of the transmitter at your accustomed distance.
The key fob should work normally after replacing the battery and should not need to be reprogrammed.
If the inside of the battery compartment of your remote is smeared with grease, do not clean or wipe the grease out. It is used to keep the battery terminals from corroding. Do no touch the circuitry of your remote transmitter when the battery cover is removed, as static electricity can damage it. Make sure the two halves of the transmitter are snapped back together properly. If not, moisture could enter the transmitter and damage it.