Last Updated on October, 2024
Imagine you’re about to leave for work in the morning or drop your children off at school, and your key fob refuses to open the car doors. Talk about a bad start to the day.
If your car key fob stops working, repeatedly pressing the unlock button will not solve the issue (though we’ve all tried it.) While there are many potential causes for a faulty key fob, the most common one is a dead battery.
Most key fob batteries will show early signs of deterioration before they expire, and it’s important to take prompt action when these signs appear.
When replacing your car key battery, you can consult your local dealership or auto locksmith, or you can do the replacement yourself.
This article will provide a step-by-step explanation of the battery replacement process, allowing you to revive your car’s key fob from the comfort of your home.
Let’s begin!
Quick Summary
- The process involves identifying the key fob and battery type, opening the fob, removing the old battery, installing a new one, closing the fob, and testing it to ensure it works.
- Ensure you don’t damage the battery compartment, taking a picture of the fob before disassembly, and possibly reprogramming the fob if the car doesn’t respond after the battery change.
- If the key fob doesn’t work even after correctly replacing the battery, it’s advisable to contact a locksmith who can diagnose and fix the problem, as they offer quicker and more cost-effective solutions than dealerships.
How to Replace Car Key Fob Battery by Yourself?
Here is a detailed yet simple 6-step guide to replacing a car key fob battery by yourself.
Identify the Fob and Battery Type
First, identify the design of your key fob and how you can open the battery compartment. Entry points typically come in the form of a notch along the side seam or a screw on the back. Identifying these will help you determine which tools to use.
Screws require a Phillips-head screwdriver, while notches require a flathead screwdriver or a similar alternative.
The size of the cell is also important when looking for a replacement battery. Key fob batteries are 3V button cells, with most key fobs using the CR2025 or CR2032 varieties. However, models like the Honda CR-V use the less common CR1620 battery for their fobs.
This information can be found on the fob’s back or in your car’s user manual. If not, you will have to remove the old battery to identify its size.
Open the Key Fob
The method for opening a car key fob varies depending on its design.
Most key fobs have a notch that you can pry to separate the two halves of the fob’s body. This opening is located along the seam that goes around the fob.
Once the notch is found, insert a flathead screwdriver into the opening and apply upward pressure. You can also do this with a coin.
Gently run the tip of the screwdriver along the seam to loosen the fasteners connecting the two halves. This will separate the top and bottom parts of the key fob and open the battery compartment.
Do not try to pry open the fob using the notch alone, as this may damage the compartment and necessitate a key fob replacement.
If your key fob does not have a notch, insert the flathead screwdriver into a point along the seam and gently push it upward. As with the earlier example, run the tip of the screwdriver along the seam, continuing to push upward until all the fasteners are loose.
If a screwdriver is unavailable, use a thin blade such as a butter knife.
On the other hand, if you have an older key fob model, you might find a screw on the back rather than a notch. In this case, you can use a small Phillips head screwdriver to turn the screw counterclockwise and access the battery compartment.
Remove the Old Key Fob Battery
Once the battery compartment is open, the next step is to remove the old battery. A key fob battery typically resembles a small silver coin positioned at the centre of the housing. Some batteries are secured to the plastic with clips.
First, use a precision tool such as a pair of tweezers to unfasten the clips. Take care during this step, as you won’t be able to install a replacement battery if these clips are damaged.
Once done, gently insert a flathead screwdriver or butter knife under the coin-shaped battery and lift it from the centre slot.
Install the New Key Fob Battery
Next, place a fresh battery in the centre slot, ensuring that the positive and negative terminals are correctly aligned.
The new battery must have the positive side in the same position for it to work. If you can’t recall the orientation of the old battery, check the back of your key cover or refer to the user manual.
Once you find the right position, press the battery into the coin-shaped slot to secure it in place.
Close the Key Fob
Once the battery is installed, it’s time to reassemble the key fob. For fobs opened via a notch or side seam, align the bottom half over the battery compartment and press down to snap it closed.
If your key fob was secured with a screw, align the top and bottom half and use a Phillips-head screwdriver to rotate the screw clockwise until they are connected.
Test Your Key Fob
Once you reassemble the key fob, test it out to ensure that it works. Point the remote control at your vehicle and press a button of your choice. If you’ve installed the battery correctly, your car should respond as it did before.
If it still doesn’t respond to the car key fob, you can try reorienting the battery. Disassemble the fob, flip the positive side the other way, and see if the problem gets solved. If not, phone your nearest locksmith to come and take a look.
Tips to Remember When Replacing Key Fob Battery By Yourself
Replacing a key fob battery is much simpler than replacing a main car battery, but still requires adherence to some basic guidelines.
- Ensure that the key does not interfere with the battery replacement process: Some car key fobs allow owners to hide the physical key inside the plastic casing when not in use. For such a device, remember to slide the car key out of the fob before opening the battery compartment.
- Take a picture of your key fob before replacing the battery: Each time you disassemble and reassemble your key fob, you increase the chance of involuntarily damaging it. By taking a photo, you’ll know what the housing is supposed to look like and how the new battery should be oriented.
- Avoid damaging the battery compartment: Even a brand-new battery will not make your key fob work if it has faulty electronics or wiring. Use tweezers to loosen the clips or fasteners securing the old battery to the plastic. Ensure that wires or antennas are not disturbed when lifting them from the coin-shaped slot.
Should the Key Fob Be Reprogrammed Once the Battery is Replaced?
In most cases, you do not need to reprogram your car’s key fob once a new battery is installed. However, alterations to the wiring or circuit board might sever the fob’s connection with your vehicle. In this case, you’ll need to reestablish the connection to get the car to respond.
Follow these instructions to reprogram your car’s key fob:
- Insert the metal car key into the ignition lock.
- Rotate the key into the ON position, which will activate the electrical system without starting the engine. From ON, switch back to LOCK mode.
- Repeat this process until the car resets. A ringing sound or melody usually indicates this.
- Once the reset is done, push the lock and unlock buttons on your key fob. The car will memorise these commands and respond accordingly the next time you use them.
What Happens When a Key Fob Battery is Low?
Car remotes often lose performance and responsiveness when their battery life is low. Here are some indicators that the battery in your key fob is about to expire.
- It can no longer unlock your car from a distance and only responds at close range.
- Even in close range, it takes multiple presses for the key fob to carry out commands.
- Your car fails to start the engine, as it cannot identify the signal from your key fob.
When Should You Call a Locksmith?
Sometimes, your car may not respond to the key fob even if you’ve replaced the battery correctly and double-checked the installation. In this instance, your next course of action is to call an auto locksmith.
You may have accidentally damaged the internal wiring with your tools during replacement. A professional such as a locksmith can diagnose the problem fairly quickly and advise you on how to proceed. If needed, they will replace your non-functioning key fob with a working one.
We recommend consulting a locksmith over a car dealership because they are cheaper and quicker and will often provide on-location assistance.
Relevant guides:
Conclusion
There’s nothing worse than losing access to your car at an inconvenient time. Paying attention to signs of low battery life in your key fob will help you prepare in advance for when it expires.
As this article shows, it takes just six easy steps to replace the battery in your key fob and help you resume business as usual.
Ensure to use the right battery type and follow appropriate safety measures when making the change. If your key fob still doesn’t work, don’t panic. One phone call and your local locksmith will diagnose the issue in no time!
Best of luck!
