Can I Replace a Key Fob Battery Myself? When to DIY and When Not To
Yes, in most cases you can replace a key fob battery yourself. It takes about five minutes, needs only a small plastic tool, and the battery costs a few dollars. You do not need to reprogram the fob in the vast majority of cars. The main exceptions are sealed fobs with no opening, cracked or damaged cases, and the rare vehicles where the maker recommends a dealer visit; this guide shows how to tell which situation you are in.
Quick answer
Do it yourself if the fob has a visible seam, screw or release button and you can read the battery code once it is open. Use a plastic tool, photograph the battery before you remove it, and test the buttons afterwards. Ask a locksmith or dealer if the fob is sealed, cracked, or still dead after a fresh correct battery.
How hard is it?
Changing a key fob battery is one of the easiest bits of car maintenance. There are three skills involved: opening the case, noting the battery direction, and closing the case again. None of them need tools beyond a coin or a small screwdriver. If you can change the battery in a watch or a TV remote, you can change one in a key fob.
What you need
- The correct battery (see below).
- A small plastic pry tool, a coin, or a small Phillips screwdriver, depending on the fob.
- A phone to take a “before” photo.
- A clean table and a soft cloth.
Step by step
- Find the battery type. The code (CR2032, CR2025, CR2016, CR1620) is on the old battery or in the manual. See the key fob battery size chart.
- Open the fob. Look for a notch, screw, release button or sliding cover. Our guide on how to open a key fob covers each one.
- Photograph the battery and note which side is up. The polarity guide shows how to tell positive from negative.
- Swap the battery with a plastic tool, holding the new one by its edges.
- Close and test every button next to the car.
For battery-specific walkthroughs, see the CR2032 replacement guide or the CR2025 replacement guide.
Benefits of doing it yourself
- Saves money. The battery itself costs a few dollars, while shops and dealers may add a labour charge.
- Saves time. You do not have to book or travel.
- You choose the battery. You can buy a fresh, branded cell instead of whatever a shop has in stock. See best CR2032 batteries for key fobs.
- You learn the fob. You will know how it opens and which battery it uses for next time.
When you should not do it yourself
- The fob is sealed. A few fobs have no visible opening. Do not cut into the case. Check the manual or ask the dealer.
- The case is cracked or the clips are broken. A locksmith can fit a replacement shell.
- The manual says to use a dealer. A small number of manufacturers recommend this for certain keys.
- The fob has water damage or corrosion. A new battery will not fix a damaged board.
- You are not comfortable. It is fine to ask for help.
Will the fob need reprogramming?
Normally not. Most fobs keep their pairing in non-volatile memory, so a quick battery change does not erase it. If the fob stops working afterwards, check the battery direction and contacts first. Our article on whether a key fob needs reprogramming after a battery change explains the exceptions.
Risks of DIY and how to avoid them
| Risk | How to avoid it |
|---|---|
| Scratching or cracking the case | Twist a coin or use a plastic tool; do not pry with a large metal screwdriver |
| Bending the battery contacts | Use plastic tools and lift the cell gently |
| Wrong battery size | Match the code printed on the old battery |
| Battery in backwards | Photograph the old one first |
| Losing small parts | Work over a tray or cloth |
| Child or pet swallowing a coin cell | Keep old and spare batteries out of reach |
DIY, locksmith or dealer?
| Option | Best when | Things to know |
|---|---|---|
| Do it yourself | The fob opens easily and you know the battery code | Cheapest and quickest; you handle the small parts |
| Locksmith | The case is damaged, or you want it done fast | Often quick and may come to you; ask the price first |
| Dealer | The fob is sealed, or the manual recommends it | May charge more; you may need to book |
| Shop or kiosk | You are out and about and need a quick change | Check the battery brand and expiry date |
Prices vary widely by area, so ask for a quote before agreeing. In many cases the cost of the labour is far more than the battery.
Tips for your first time
- Watch where the clips are before you press. Most fobs have one or two snap points at the seam.
- Do the job in good light, over a table, so small parts do not disappear.
- Keep the fob closed in your hand while you press the seam, so the two halves do not fly apart.
- Do not remove the circuit board unless you have to. The battery is normally accessible without it.
- If something does not feel right, stop and look again rather than forcing it.
- Take the photo before and after. It is the easiest way to remember how things go together.
How long does it take?
For a fob you have never opened, allow ten minutes, since most of the time is spent working out how it opens. Once you know, the battery swap itself takes under two minutes. Smart keys with a hidden key blade take a little longer than a simple remote, and fobs with a screw take a little longer than ones with a snap.
Does a DIY battery change affect the warranty?
A battery is a consumable part, and changing it is normal maintenance. As long as you do not damage the fob, changing the battery does not usually affect a vehicle warranty. If you are unsure, check the warranty booklet, or ask the dealer before you open a fob that is still under warranty.
What if the battery dies away from home?
Most keys have a hidden mechanical blade that opens the driver’s door. After that, many smart-key vehicles let you start the car by holding the fob against the start button or a marked area, because the car can read a nearby chip even when the battery is flat. The exact method depends on the car, so look it up in the manual before you need it. A shop or pharmacy often sells the right battery, so you can swap it on the spot if you have the tools.
Before you buy: a short checklist
- Read the code on the old battery, or look it up in the manual.
- Check the size on the pack: CR2032 is not CR2025.
- Look at the expiry date on the pack.
- Choose a recognised brand.
- Consider a two-pack.
If you are not sure which of the two common sizes you need, see CR2032 vs CR2025.
Things you should not use
- A large metal screwdriver to pry the case. It scratches and cracks the plastic.
- A knife blade. It is easy to slip and cut yourself or the board.
- Superglue or tape to close a broken case, unless a locksmith advises it.
- Two batteries stacked to make up a missing thickness.
- A rechargeable coin cell such as LIR2032, which runs at a higher voltage.
What to do if it does not work afterwards
- Check the battery direction.
- Check the code, and try a second new battery.
- Clean the contacts with a dry cloth.
- Test the spare fob.
- If everything is correct and the fob is still dead, it may need re-pairing or repair.
Our guide on what to do when a battery replacement did not fix the problem goes through each step.
How often will you have to do this?
Often every few years. How long a battery lasts depends on how the fob is used; see how long key fob batteries last and how often to replace a key fob battery.
Choosing a battery
Check the code, buy a recognised brand, check the expiry date, and keep a spare at home. You can browse CR2032 batteries on Amazon. As an Amazon Associate, ReplaceKeyFob earns from qualifying purchases; see our disclaimer.
Safety: keep coin batteries away from children and pets
A swallowed coin cell can cause serious internal burns within hours. Keep spares and old cells out of reach. If you think a child has swallowed a battery, go to the emergency room straight away and call the National Battery Ingestion Hotline at 1-800-498-8666, or Poison Help at 1-800-222-1222. More guidance: Poison Control.
Frequently asked questions
Can I change my key fob battery myself?
Yes, for most fobs. It takes a few minutes with a small plastic tool and the right battery.
Do I need special tools?
Usually not. A coin, a plastic pry tool or a small screwdriver is enough.
How much does it cost to have a key fob battery replaced?
The battery costs a few dollars. If you use a shop, dealer or locksmith, expect to pay extra for labour, and prices vary by place.
Will changing the battery erase my key fob?
Not normally. The fob keeps its pairing. Check the direction of the battery if it does not respond.
What if I put the battery in wrong?
It usually will not work. Take it out and turn it over. Do not leave it in backwards.
Can a dealer do it for free?
Some do, as a courtesy, but it is not guaranteed. It is best to ask.
Which battery does my fob use?
Most use a CR2032 or CR2025. Check the old battery or the manual.
Bottom line
For most owners, changing a key fob battery is an easy five-minute job. Match the battery code, copy the direction, use plastic tools, and test it. If the fob is sealed, damaged or still dead with a new battery, ask a locksmith or dealer.