How to Replace a Key Fob Battery

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Key fob (Photo: @TonyTheTigersSon via Twenty20)
Although much easier to use, car key fobs come with their own challenges. You may not have to pull out your freezing brass keys to unlock your door in a snowstorm or potentially lock your keys in your car, but you will, however, eventually need to learn how to change the fob’s battery.
There are many things that factor in to how long your key fob’s battery will last; however, the average battery lasts about five to six years.
So, you’re 5-ish years into owning your car — it’s happened — your key fob is dead. Here’s what you do.

How to open a key fob

Key fobs come in all shapes and sizes so there is no one way to open their cases; but here are a few ways you can attempt opening your key fob’s cover. Remember, if your key fob has faced some wear and tear, its outer shell might be brittle. Do your best not to wrench it open.
Tab: There might be a recessed tab on the backside of the device that you press down on to access the battery.
Screws: Some fob panels may need to be unscrewed with a small screwdriver or the side of a coin.
Casing containers: Fobs without screws or secret spring panels need to be (gently) pried open using makeshift tools and sheer force. Take a small screwdriver, a nail file, or even the tip of a key and wedge under the back panel seam to lift.
When in doubt, read your owner’s manual. You kept it in your everything drawer for exactly this reason.

How to remove a key fob battery

Once you’ve opened the fob, the next step is locating and removing the battery. Most fobs use small lithium coin cell batteries that can be easily removed by hand. Take note of the position of the battery before removing so you know which way to place the new battery. Typically, the + side of the battery should be facing up.
Refer to the serial numbers printed across the battery to determine which type you need. You should have no trouble finding a replacement at any hardware store, big-box retailer, or online. The most commonly used key fob batteries are the CR2032, CR2025, CR1616, CR2032, and CR1632. The C indicates that it is a lithium battery while the R refers to its round shape.
Once you have your new battery in hand, place inside the open fob exactly how the old battery was installed, and snap, press, or screw the fob casing closed.

Testing your key fob

Now it’s time to test your new battery. If the remote functions of your key fob still aren’t working properly, it may be because the replacement battery is positioned incorrectly. Open up the fob, flip the battery, and test it again. If the second test is still unsuccessful, the key fob may be broken.

What to do if your key fob is broken

At this point, it’s a good idea to take the key fob to your mechanic for a closer look. If the mechanic recommends purchasing a new key fob, it’s often much cheaper to order a replacement online from a third-party vendor and then have it programmed at a dealership. The downside of this is there is no guarantee that you’re getting a quality device. If you decide to purchase your key fob at a dealership, however, it will probably come with a warranty.