A key fob battery is essential for locking, unlocking, and even starting your car. But, like any battery, it eventually loses power, causing the remote to become unresponsive.
Fortunately, replacing a key fob battery is quick and easy, taking only a few minutes.
In this guide, we’ll cover how to change the battery in a key fob, reprogram it if needed, and identify the key signs that indicate it’s time for a replacement.
Let’s begin!
This Article Contains:
- How to Change Battery in Key Fob: A Step-by-Step Overview
- How to Reprogram a Key Fob After Installing the New Battery
- 4 FAQs about Car Key Battery
How to Change Battery in Key Fob: A Step-by-Step Overview
Replacing the car key fob battery is an easy DIY task. However, before you start replacing the battery, ensure you have the following tools handy:
- A thin blade (e.g., watch knife) to open the fob case
- Correct replacement battery type (usually a CR2025 or CR2032 battery)
- Small screwdriver (1.4mm to 2.4mm)
Once you have all the necessary tools, follow these steps to replace the key fob battery:
Step 1: Open the Key Fob
If your key fob has a mechanical key, move it aside to access the battery. For example, in car models like Ford and Honda, you need to press the side button or back switch and lift the silver top to remove the metal key (refer to your owner’s manual for exact instructions).
Next, check if there is a screw on the back of the fob (common in older key fobs). If present, use a small Phillips head screwdriver to remove and store it safely. Once the screw is removed, locate the seam where the fob opens.
If you see a tiny notch, insert a small flathead screwdriver or a coin into it and twist gently to separate the halves. If there is no notch, pry open the fob along the seam with caution.
NOTE: To open car key fobs with a removable metal key, insert the key into the slot inside the key cavity and gently pry it open.
Step 2: Remove the Old Battery
Inside the fob, you will find a small, round coin battery. If your key fob has a battery cover, remove it first. Then, use the small flathead screwdriver to lift out the battery. If clips hold the old key fob battery in place, carefully lift them to avoid damage.
Once you’ve removed the old battery, store it safely to dispose of at the recycling center later.
Step 3: Insert the New Key Fob Battery
Check the battery orientation (+/- markings inside the battery compartment or the fob’s cover) to ensure you place the new battery correctly. Slide the replacement battery into place and press down gently to secure it.
While most car key fobs use a CR2025 or CR2032 battery, others may require a CR1620. If unsure, check the owner’s manual for instructions on the correct battery size.
Step 4: Reassemble the Key Fob
Once the new key fob battery is installed, reattach the battery cover (if any), then align the two sides of the fob and press them firmly so that they snap back into place.
If your fob has a screw, use the small Phillips head screwdriver to tighten it back. Ensure the fob is securely closed to prevent the battery from shifting.
Step 5: Test the Key Fob
After reassembling the key fob, point it at your car and press a button to check if it works. If the fob doesn’t respond, reopen it to verify the battery orientation and ensure you’ve installed the right battery.
If the issue persists, your key fob may need reprogramming or a complete replacement. Call a mechanic or use your replacement key to drive to the nearest service center for assistance.
Can’t find a reliable mechanic nearby?
Let’s see if you can reprogram the key fob yourself.
How to Reprogram a Key Fob After Installing the New Battery
If your car key fob stops working after a battery replacement, it may need to be reprogrammed to sync with your vehicle.
Follow these steps to reprogram your key fob:
Method 1: Standard Reprogramming
- Use the physical key to unlock your car manually, then sit inside and close the door.
- Insert the physical key into the ignition.
- Turn the key to the “run” position (without starting the engine) and then back to “lock” several times.
- Listen for a chime or beep, indicating the system is in programming mode.
- Press the “lock” or “unlock” button on the key fob. If the pairing is successful, you’ll hear another chime.
- Test the remote to ensure it’s working properly.
If this method doesn’t work for you, here’s an alternative you can try:
Method 2: Alternative Reprogramming
- Enter the car using the mechanical key and close the door.
- Insert and remove the key from the ignition six times within 10 seconds.
- If this is the correct sequence for your vehicle, the interior and exterior lights will flash.
- Insert the key again and turn it to accessory mode.
- Press any button on the key fob. If the pairing is successful, the hazard lights will blink.
- Test the fob to confirm it’s working correctly.
If neither method works, your key fob may require professional reprogramming. For this, visit an authorized service center specializing in your car’s make and model.
Now, let’s address some other questions you may have about key fob batteries.
4 FAQs about Car Key Battery
Here are the answers to some commonly asked questions about replacing a key fob battery:
1. How Much Does a Key Fob Battery Replacement Cost?
A CR2032 or CR2025 coin battery type typically costs between $2 and $10. However, if you choose to have it replaced at a dealership or service center for convenience and reliable service, the total cost, including labor, can range from $20 to $50.
2. What Are the Signs Your Key Fob Battery Needs Replacement?
Here are the symptoms you’ll notice if your fob has a weak or dead battery:
- The door locks don’t respond when you press the button
- The fob works intermittently
- The trunk release button doesn’t work
- Remote start fails to turn on the car
- The panic button doesn’t respond
3. Can You Test a Key Fob Battery?
Yes, you can test if your key battery is weak by checking its voltage with a multimeter. Most key fob batteries, like the CR2032, should read around 3V. If the voltage is below 2.7V, the battery is too weak and needs replacement.
4. Why Isn’t Your Key Fob Working Despite Replacing the Battery?
If your key fob doesn’t work even after a battery replacement, the problem might be something else. Here are a few possible issues:
- Damaged key fob: Water damage or physical impact from frequent dropping can stop the device from working.
- Worn buttons: Dirt or wear can make the key fob buttons unresponsive.
- Battery connection issues: Broken or damaged terminals in the battery compartment or circuit board can prevent the key fob from working.
- Faulty locks: Sometimes, the fob may be fine, but the car won’t respond. In such cases, test the locks manually and get them repaired if needed.
- Deprogrammed fob: Pressing the fob buttons too many times while out of range or disconnecting the car battery can deprogram the key fob.
Get Your Key Fob Working Again with AutoNation Mobile Service
Replacing an old key fob battery is simple, but if you can’t open it or get your car to start even after installing a new battery, it’s best to seek professional help.
Don’t want to deal with the hassle of visiting a repair shop?
AutoNation Mobile Service brings expert assistance straight to your driveway.
We’re a mobile car repair and maintenance solution offering upfront pricing, online bookings, as well as a 12-month, 12,000-mile repair warranty.
Whether finding the right battery size, replacing the dead battery, or reprogramming the key fob — our mechanics can get your key device working again quickly and at your convenience.
Contact us today for all your car repair needs.