Most key fob batteries come out by sliding or prying open the case
You can replace a key fob battery yourself in most cases without tools or a trip to the dealership. The battery sits inside a plastic case that either slides apart or pops open with gentle pressure from a coin or flathead screwdriver. Once you remove the old battery, you note its size and type — usually printed on the battery itself — buy a replacement at any drugstore or supermarket, and snap the case back together.
The whole job takes about five minutes. The only real risk is cracking the plastic case if you pry too hard, but even that is repairable with a small amount of adhesive. Most people find this easier than calling a dealer or waiting for an appointment.
Key Takeaways
- Key fob cases open by sliding the two halves apart or by prying gently with a coin or flathead screwdriver along the seam.
- The battery type and voltage are printed on the battery itself, so you can match it exactly when you buy a replacement.
- Common key fob batteries like CR2032, CR2025, and CR2016 cost between one and three dollars at pharmacies, grocery stores, and online retailers.
- If the case is stuck, soak the seam in warm water for a few minutes or use a plastic spoon instead of metal to avoid scratching.
- After inserting the new battery, test the fob before closing the case completely to make sure the buttons respond.
Identify your battery type before you buy a replacement
Open the key fob case first, then look at the battery itself. The type is stamped directly on the metal surface — you will see something like CR2032, CR2025, CR2016, or similar. Write this number down or take a photo with your phone so you have it when you shop.
If you cannot read the number clearly, the battery is usually a standard coin cell, and the most common size for car key fobs is CR2032. You can also bring the old battery with you to the store and match it to a replacement, or ask a pharmacy technician to identify it.
Open the case by sliding or prying along the seam
Most key fob cases split into two halves held together by a thin plastic seam. Look for a small slot or notch along one edge — this is where you explore pressure. If you see a slot, insert a flathead screwdriver or coin into it and twist gently until the case pops open. Do not force it; if it does not budge after light pressure, try the opposite edge.
If there is no visible slot, the case slides apart instead. Hold one half firmly and slide the other half toward you or away from you along the seam. Again, gentle pressure is all you need. If the case is stuck, soak the seam in warm water for two or three minutes to soften any adhesive, then try again. A plastic spoon works better than metal for this step because it is less likely to scratch the plastic.
Remove the old battery and insert the new one
Once the case is open, you will see the battery sitting in a small compartment, usually held in place by a metal contact or a small plastic clip. Gently pry the battery out with your fingernail or a plastic tool. Do not use a sharp metal object, as this can damage the compartment.
Before you insert the new battery, check the orientation. Most coin cell batteries have a flat side and a slightly raised side. The flat side usually goes down, facing the metal contact, but look at how the old battery was positioned and match that. Slide the new battery into place, making sure it sits flat and find. If there is a metal clip, it should hold the battery snugly without being so tight that you cannot remove it later.
Test the fob before closing the case
Press each button on the fob — lock, unlock, trunk, panic, or whatever buttons your fob has — and listen for a click or feel for a vibration. If the fob responds, the battery is installed correctly and the case is making good contact. If nothing happens, remove the battery and flip it over, then try again. The orientation matters.
Once the buttons work, close the case by reversing the opening step. If the case slides, push the halves together firmly until you hear a click. If it pops open, press down along the seam until the two halves are flush. You may hear or feel a small snap as the case locks.
Where to buy replacement batteries
Coin cell batteries are sold at pharmacies, grocery stores, big-box retailers, and online. Common places include CVS, Walgreens, Target, Walmart, and Amazon. Prices range from one to three dollars per battery, and you can often find them in the watch or hearing aid section, or near the checkout counter. Some stores sell them in multipacks, which is useful if you have more than one fob or want spares on hand.
If you cannot find the exact type locally, ordering online usually takes one to two days with standard shipping. Buying in person means you can test the fob when ready and return to the store if something goes wrong, so that is often the faster route.
What to do if the case will not open or the fob still does not work
If the case is cracked or the seam is damaged, you can still replace the battery, but you may need to hold the case together with a rubber band or a small amount of waterproof adhesive after you close it. Silicone sealant or a two-part epoxy works well for this and does not interfere with the buttons.
If you replaced the battery and the fob still does not work, the problem is usually the orientation of the battery or a poor connection between the battery and the metal contact. Remove the battery, clean the metal contact inside the case with a dry cloth or a pencil eraser to remove any corrosion, and reinsert the battery in the opposite orientation. If that does not work, the circuit board inside the fob may be damaged, and you will need to replace the entire fob — your car's dealership or a locksmith can order one for you.
Frequently Asked Questions
Can I use any coin cell battery, or does it have to be the exact type?
Use the exact type printed on your old battery. CR2032, CR2025, and CR2016 are all different sizes and voltages, and using the wrong one can damage the circuit board or cause the fob to malfunction. The cost difference is minimal, so matching the type exactly is worth the effort.
What if I lose the battery or drop it inside the case?
If you drop the battery inside the case, tilt the fob gently and tap the back until the battery slides out. If you lose it, you already have the type number from the old battery, so you can buy a replacement and start over. Keep the case open on a clean surface while you work to avoid losing small parts.
Do I need to reprogram the fob after changing the battery?
No. Changing the battery does not erase the fob's programming. As soon as the new battery is in place and making contact, the fob should work exactly as it did before. If it does not, the problem is the battery orientation or connection, not the programming.
How often do key fob batteries need to be replaced?
Most key fob batteries last three to four years with normal use. If you use the fob frequently, the battery may wear out sooner. You will notice the buttons becoming less responsive or requiring harder presses before the fob stops working entirely. When that happens, it is time to replace the battery.
Is it safe to throw away the old battery?
Coin cell batteries contain small amounts of lithium or other materials and should not go in the regular trash. Most pharmacies and retailers that sell batteries also accept old batteries for recycling at no charge — just ask at the customer service desk. Some communities also have battery recycling programs through their waste management system.