Most key fob batteries take five minutes to swap out yourself
A key fob battery usually dies gradually — your remote stops working from farther away, then stops working altogether. You can replace it yourself without tools or a trip to the dealership. The battery itself costs between $3 and $10, and the whole job takes about five minutes once you have the new battery in hand.
The steps are nearly identical across most car brands, though the exact way your fob opens varies slightly. This guide covers the most common designs. If your fob has an unusual shape or your owner's manual shows a different method, follow what the manual says — some fobs are designed to open in a specific way to avoid damage.
Key Takeaways
- Most key fobs use a CR2032 or CR2025 battery, which you can buy at any drugstore, grocery store, or hardware store for a few dollars.
- The fob usually opens by sliding a small metal lever, pressing a hidden button, or prying gently at a seam — check your owner's manual if you are unsure which method applies to yours.
- When you open the fob, note which side of the battery faces outward so you can install the new one the same way.
- If the fob still does not work after you replace the battery, the problem may be a broken button contact or water damage inside the fob rather than the battery itself.
Finding out what battery your fob needs
The easiest way is to open the fob and look at the battery itself. The battery will have a code printed on it — usually CR2032, CR2025, or CR2016. Write down that code or take a photo with your phone.
If you cannot open the fob or the battery is too worn to read, check your owner's manual. The manual usually lists the battery type in a section about the key fob or remote. You can also call your car's dealership with your vehicle identification number (VIN) and they will tell you the correct battery type, though this takes longer than looking it up yourself.
Once you know the type, buy a replacement at a pharmacy, grocery store, or hardware store. These batteries are inexpensive and widely stocked. Avoid buying the absolute cheapest option — a mid-range battery from a known brand will last longer and cost only a dollar or two more.
Opening the key fob safely
Most fobs open one of three ways. Look at your fob first to see which applies to yours, then use that method.
Sliding lever method: Look for a small metal or plastic lever on the edge or back of the fob. Slide it in the direction the arrow points (or away from the center if there is no arrow). The fob should split into two halves. If it does not budge, you may be sliding in the wrong direction — try the opposite way.
Hidden button method: Some fobs have a small button recessed into the back or side. Press it firmly with a pen or the edge of a coin. The fob should pop open or the back should slide off. If nothing happens, try pressing other small indentations on the fob.
Pry method: If you see a seam running around the edge of the fob, use a flat tool like a butter knife, coin edge, or flathead screwdriver to gently pry at the seam. Start at one corner and work your way around. Do not force it — if it resists, you may be using the wrong method. The two halves should separate with gentle, steady pressure.
Once the fob is open, set the two halves where they will not roll away. The battery will be sitting in a small metal or plastic holder inside.
Removing the old battery and installing the new one
Look at how the old battery sits in its holder. The side facing up will have a + or − symbol printed on it. Remember which symbol is facing up — this matters for the new battery.
Lift the old battery out gently. If it is stuck, use a plastic spoon handle or the edge of a coin to nudge it up from underneath. Do not use anything sharp that could scratch the inside of the fob.
Take your new battery and orient it so the same symbol (+ or −) faces the same direction as the old one did. Place it in the holder and press down gently until it sits flat. You should hear or feel a small click as it settles into place.
Close the fob by reversing the method you used to open it. If you slid a lever, slide it back. If you pried it open, press the two halves together until they click. If it has a button, press it to close. The fob should feel solid when closed, not loose or rattling.
Testing the fob and troubleshooting if it does not work
Stand a few feet from your car and press each button on the fob. You should see the car's lights flash or hear the locks click. If nothing happens, open the fob again and check that the battery is seated properly and facing the correct direction. Close it and test again.
If the fob still does not work after you have checked the battery twice, the problem is likely not the battery. The most common causes are a broken button contact inside the fob (which requires replacing the fob itself) or water damage that corroded the electronics. If you see any corrosion — green or white crusty buildup — inside the fob, the fob may not be repairable.
As a backup, most cars have a physical key hidden inside the fob itself. Look for a small slot or seam on the fob and slide or pry to reveal the key. You can use this to unlock your car manually while you decide whether to replace the fob.
When to replace the whole fob instead of just the battery
If the battery is new and the fob still does not work, or if you see visible damage, corrosion, or cracks inside the fob, replacing just the battery will not help. You will need a new fob.
A replacement fob from a dealership typically costs $200 to $500 and may need to be programmed to your car. Some dealerships charge extra for programming. Aftermarket fobs from online retailers cost $30 to $100 but may not work with all car models — check the listing carefully to make sure it matches your vehicle year and model.
If you buy an aftermarket fob, you will usually need to program it yourself or take it to a locksmith. Programming instructions vary by car make and model. Your owner's manual or the fob's packaging should include steps, or you can search online for "[your car year and model] key fob programming."
Frequently Asked Questions
Can I use a different battery type if I cannot find the exact one?
No. Battery types like CR2032 and CR2025 look similar but have different thicknesses and voltages. Using the wrong type can damage the fob's electronics or cause it to malfunction. Stick with the exact type listed in your manual or printed on the old battery.
What should I do with the old battery?
Most batteries can go in your regular trash, but some areas have recycling programs for batteries. Check your local waste management website or ask at a pharmacy — many accept used batteries for free. Do not throw lithium batteries in a fire or expose them to extreme heat.
Why does my fob battery die so quickly?
Batteries typically last three to four years with normal use. If yours dies much faster, you may be pressing the buttons more often than you realize, or the fob may have a small leak letting moisture inside. If the new battery also dies quickly, have a locksmith or dealership inspect the fob for water damage.
Do I need to reprogram my fob after changing the battery?
No. Changing the battery does not erase the fob's programming. It should work when ready once you install the new battery and close the fob. If it does not, the problem is not the battery replacement — it is something else wrong with the fob.