I love my remote key-less entry, but over the past few weeks I have noticed that my car key fob is not locking my car exactly like it should. It is okay to have to press the button twice, even a few times, but when I have to start shaking the key fob and hitting it on my hand to try and get the doors unlocked one more time, then I guess it is time to replace the battery.
The hardest part of replacing the battery is getting the key fob open without breaking it. I took a good look at mine and noticed that at the top there was (1) a small hole to help open it. Some fobs will have something similar on the other end, a sliding door on the back or a coin turn opening on the back. I used a small pair of scissors (2) to open up the fob and (3) found the battery.
Take note of the way your old battery is installed. My battery was installed with the + side down. Some key fobs do not have a marking to indicate + or - when you install the new battery. Once I got the key fob opened I noted that I needed a coin cell or button CR2032 battery. To break down the number that means I needed a (C) Lithium (R) Round (20) 20mm (32) 3.2mm battery. You will probably need something similar for your key fob. You can find Coin Cell Batteries at Batteryheads.
Do not remove old battery with metal object as that can damage circuitry. Remove old battery If there is any oil or grease in the key fob, do not remove it. It is there to help prevent corrosion. Do not touch or remove circuitry as that may damage it. Now install new battery with +/- the same direction as old battery.
The last step is to reverse the process and put your key fob back together. Make sure all pieces are lined up correctly and then put back together. If your key fob snaps shut, make sure it is snapped tightly so the two sides do not come apart.
Replacing battery should not alter your programming. You are now set to lock your locks with your remote key-less entry!
Please dispose of you coin cell batteries correctly and promptly. They are harmful if swallowed.