Battery-operated key fobs enable you to unlock the doors of your vehicle remotely. Some key fobs are sophisticated enough to let you turn on lights and even start the engine of your vehicle before you get in it. A key fob is fairly small and therefore so is the battery. While a battery can last more than a year, it's important not to let the battery go dead; otherwise, you will need to find your emergency metal key. If you find that you're getting nearer and nearer to your vehicle before the doors unlock remotely, you need to change the battery in your key fob.
Use a small flathead screwdriver to pry open the two halves of the key fob. Most key fobs clip together so you can change the battery relatively quickly. Carefully insert the screwdriver between the two edges; there's usually a specific place for you to do this, then slightly twist the screwdriver so the two parts separate.
Put the top half of the key fob to one side. The bottom half contains the battery.
Look at the bottom half of the key fob to ascertain how the battery is fitted. It may have a small battery cover that's held in place by Phillips screws, so use a suitably-sized screwdriver to remove the small screws, lift off the cover and remove the battery using your fingers. Some key fob batteries are held in a metal slot, so use a small flat head screwdriver to push the battery from the slot, then remove the battery using your fingers. Alternatively, the battery may simple rest on the terminal in the base of the key fob, so just lift it out using your fingers.
Check the key fob to find out which way the battery needs to be placed. Key fob batteries are small button cell batteries. The flat plate on the top of the battery has a "+" embossed on it to indicate positive. The other side is slightly raised and doesn't have a label, but is the negative terminal. The key fob terminals are clearly marked "+" and "-", so you need to make sure the "+" side of the battery connects to the "+" terminal in the key fob.
Put the replacement battery into the bottom half of the key fob using a reversal of the method you used to remove it. Place it on the base unit if it just rested on the terminal or slide the battery into the slot using your fingers. If the battery has a battery cover, put the cover over the battery compartment and replace the screws. Tighten the screws using a screwdriver.
Put the top half of the key fob onto the bottom half. Use your fingers to press the two halves together until you hear and feel them click.
Key fob battery replacement can be slightly different to the above steps, as there are hundreds of different types. Most are fairly easy to work out and are the same or similar to the above steps. If you are in doubt or can't figure it out, check your vehicle manual as it's likely to describe how to do the task. Alternatively, contact your vehicle supplier to get instructions.