Key Fob Battery Replacement: A Complete Change the Battery in Your Key Fob

A key fob is a small wireless remote that locks and unlocks your car doors or starts your car engine. The key fob runs on a small, replaceable coin battery that powers all of its functionality. Over time, this battery will eventually drain and need to be replaced to maintain proper key fob operation.

Replacing the battery yourself is an easy, low-cost alternative to paying for replacement at the dealership. This complete do-it-yourself guide will walk through when to change the key fob battery, what you’ll need, step-by-step instructions, troubleshooting tips, and more. With a few basic tools and a new battery, you can be back unlocking your doors in no time.

When to Replace the Key Fob Battery

Knowing when it’s time to replace your key fob battery is important to maintaining the convenience and security of keyless entry. Waiting too long can leave you inconvenienced and struggling to access your vehicle.

Signs It’s Time for a New Battery

There are a few clear signs that indicate a depleted key fob battery that requires swapping out for a fresh one:

Reduced Operating Range: The key fob remote works within a certain range from the vehicle. As the battery wears down, this distance gets shorter and shorter. If you have to be closer than about 10-20 feet, the battery likely needs attention.
Intermittent Functionality: A low battery may cause the key fob to work sometimes and not others. If your remote temperamental response, a replacement is likely needed.
Warning Light or Message: Some vehicles will display a warning indicator light or text banner indicating the key fob battery is low. Heed this indicator and promptly swap in a new power source.

Additional signs that your key fob battery requires replacement:

Delayed response time unlocking/locking doors
Failure to remotely start the vehicle engine
Flickering or dim transmitter light when buttons pressed

Do not ignore these signs of a weak battery! As voltage drops critically low, the key fob can cease functioning entirely leaving you unable to access your vehicle.

Gather Necessary Replacement Supplies

Before starting the battery replacement process, gather everything you’ll need for smooth sailing:

Proper Replacement Battery: Your vehicle likely requires a standard CR2032 coin cell battery. Check your owner’s manual or existing battery to confirm. Match voltage, dimensions, and polarity precisely.
Small Precision Screwdriver: The right tool makes it easy to pry open the fob casing without damage. A #0 Phillips head or thin flathead driver does nicely.
Clean Cloth: Use this to clear away dirt, oils, or debris without risk to circuits. A cotton pad or swab works great.
Flashlight: Good visibility ensures you properly realign components and avoid accidentally touching electronics.

Having all your supplies prepped in advance cuts down on potential delays and frustration of swapping out batteries. Don’t wait until that weak battery leaves you stranded!

How to Change the Key Fob Battery

Swapping out the battery on most modern, wireless-equipped car key fobs takes 5-10 minutes for the DIYer. The process simply involves opening the shell, removing the old power source, installing fresh batteries in the proper orientation, reassembling the unit, and testing the operation.

Overview of DIY Battery Replacement Process

When replacing the battery yourself, you essentially have two options:

1. Do-It-Yourself (DIY): This path requires a new battery, a small screwdriver, a cloth, a flashlight, and patience/care. But the total cost is under $5 if you have tools/light already.
2. Dealership Service: Your area dealer may replace for $30-$60 typically. However, prices in some areas reportedly exceed $150 including new key fob fees if failure occurs!

Unless you have an older model or temperamental fob design, DIY battery swapping is the clear choice. Just carefully follow instructions, avoid touching components, use anti-static methods, and work near soft surfaces in case of drops.

Step-by-Step DIY Key Fob Battery Replacement Instructions

Refer to your owner’s documentation for model-specific guidance, but most units follow a similar process:

Recommended Key Fob Replacement Tools/Supplies

Proper Replacement CR2032 Battery in your key fob
Small Phillips & Flathead Screwdrivers
Cleaning Cloth/Cotton Swabs
Flashlight for Visibility
Anti-Static Brush (optional)

1. Turn the key fob over & note the brand name/model number for specific guidance.
2. Locate the seam securing the upper and lower casings together. Identify release notches for pry tool leverage.
3. Wearing an anti-static strap if available, carefully wedge the flathead screwdriver tip into the seam notch to pop open the housing. Take care not to bend or crack plastic.
4. Once freed, carefully pivot shells apart & use a flashlight to illuminate the battery location and adjacent components.
5. Slide the depleted battery out from mounting brackets/clips using a plastic pry tool or fingertips. Avoid pulling on connected wires! Lift directly out instead.
6. Visually inspect battery contacts for moisture, corrosion, or debris buildup. Use a cotton swab dampened with alcohol to gently clean if needed so the fresh battery seats securely.
7. Closely check the (+) and (-) polarity orientations for the new battery against markings on the circuit board or etched arrows showing the install direction.
8. Keeping the same orientation, gently push the replacement battery flush into the mounting clip or electrical contact plates according to the etched polarity arrows nearby. Do NOT force the wrong orientation!
9. Confirm battery mounts securely in the battery bracket and that no wires interfere with casing closure.
10. Carefully snap the key fob’s upper and lower shell casing back together securely on all sides. Lightly tug the seam to ensure a tight seal.
11. Press every key fob button several times to confirm normal functionality before syncing back up with the vehicle.

And that’s it! As long as the polarity was aligned properly, your key fob should work as well as new after syncing.

Tips for Hassle-Free DIY Battery Swap

Follow these simple guidelines for the smoothest home battery replacement job:

Carefully pry at shell seam edges – avoid tools on ornate key fob decoration areas.
DO NOT touch the circuit board or pull wires when removing the old battery.
Check polarity against markings 3 times before installing a replacement battery.
Dampen cotton swab in alcohol to scrub corroded battery contacts if needed.
Press every button during reassembly to check for pinched wires or damage.

Overall, just remember to work slowly and gently. Avoid excess force, use anti-static methods, keep components aligned properly, and double-check everything as you work. Improper assembly can further damage the key fob.

Resetting and Re-Pairing Your Key Fob

While most battery installs immediately sync the key fob with the car correctly again, some vehicles require you also reset the device and re-pair the two systems to fully restore functionality.

Why Resetting May Be Necessary

If doors fail to lock/unlock or the vehicle won’t start remotely after a battery swap, a reset clears any stored memory and gets the key fob ready to reconnect with onboard computers from scratch.

How to Reset Your Key Fob

Resetting a key fob is quite simple:

1. Press any button repeatedly for 30+ seconds until the indicator light blinks rapidly.
2. Once blinking stops, press each button 2-3 times more to complete the memory wipe and reset.

*No reset functionality after the above steps indicates a battery or component failure may have occurred.*

Additionally, some make/models have a manual reset button underneath the battery needing to be pressed with a paperclip after battery replacement.

Others require a multi-button reset process instead:

1. Press and hold the lock and unlock buttons together for 10+ seconds.
2. With buttons still held, also press the trunk release or remote start buttons briefly.
3. Release all buttons once the key fob light begins flashing.
4. Press each key twice more to complete the reset.

Instructions for Re-Pairing with Vehicle

Common re-pairing methods are:

One-Button Auto Re-Pairing

1. Enter the vehicle, close the doors, and turn to accessory mode.
2. Hold lock + unlock buttons for 5+ seconds until hazards flash twice.
3. Press any fob button and confirm doors properly lock/unlock indicating successful sync.

Menu-Based Re-Pairing

Some automakers use the settings display menu for fob programming:

1. Scroll to Vehicle Settings > Key Fob Programming
2. Follow on-screen prompts to push certain fob buttons.
3. Turn the vehicle fully off and on once more to complete the sync process.

If functionality remains problematic after resetting and carefully attempting to re-pair, have the dealership troubleshoot potential causes. Severe electronic damage can render a key fob inoperable.

Troubleshooting Common Key Fob Issues

While most go off without a hitch, here are some troubleshooting tips for potential problems:

Key Fob Not Working After Battery Replacement

Battery possibly installed backward – carefully check polarity
Attempt master reset of key fob and re-pair with vehicle
Defective replacement battery with insufficient voltage
Physical damage to fob components during reassembly

Shortened Battery Life After Replacement

An inferior quality or counterfeit battery was likely installed
Excess push button testing prematurely drained the battery
Vehicle electrical fault causing abnormally high fob power consumption

Greatly Reduced Key Fob Range

Battery not given proper initial installation charging
Nearby electronic devices interfering with the transmitter signal
Failing battery unable to output normal energy level for full signal broadcast distance

Carefully following battery replacement steps help avoid complications, but take your time testing fixes if issues do come up. Almost any common key fob problem traces back to battery polarity, voltage, or pairing integrity.

What Type of Battery is Inside Key Fobs

The vast majority of modern automotive key fob remotes utilize a standard replaceable CR2032 3V lithium coin cell battery. This model offers a long shelf life along with adequate power capacity to reasonably support 1-4 years of normal fob operation before depletion depending on usage levels.

The CR2032 battery features:

Diameter of 20mm and thickness of 3.2mm
Rated 220-240 mAh capacity
Low self-discharge when stored
Ample voltage to drive LED transmitter
Sufficient energy density in small form

For aftermarket or replacement batteries, check for:

Expiration date code no less than 3 years future
Indications meeting IEC quality certification
Brand with a proven reputation for reliability

Top battery manufacturers include Panasonic, Energizer, Duracell, Maxell, Renata and Sony. Avoid no-name generics of suspect quality.

Properly Inserting the New Key Fob Battery

When installing a fresh CR2032 battery into your keyless entry remote, following precise polarity is absolutely vital to ensure functionality.

Closely check for permanent (+) and (-) markings near the battery contact springs or printed on the surrounding circuit board. Match alignment precisely to the new power cell prior to insertion.

If uncertain, refer to the owner’s manual diagrams or temporarily mark the existing battery using a pen before removing it so you can replicate orientation.

With polarity 100% confirmed, gently press the replacement battery flush into bracket clips or electrical contact plates without forcing or bending. Secure mounts fully indicate good contact on both terminals necessary for power flow.

If the battery is backward, the fob will fail to operate entirely. Double-checking this avoids hassles down the road!

Step-by-Step Key Fob Battery Replacement

Replacing the internal power source and keeping your keyless vehicle entry functional takes 4-5 quick steps:

1. Pry open the fob plastic housing using a screwdriver and carefully insert it into the seam
2. Gently slide out the old CR2032 coin battery from the mounts without pulling the wires
3. Use an alcohol swab to gently clean battery contacts if buildup present
4. Align (+) / (-) polarity of new battery against circuit markings
5. Press the replacement battery securely into mount clips or contact springs

Those are the basics! Avoid touching electronics, confirm thumb control & locks work again after snapping the case back tight. Resync if issues.

I’m happy to include any other helpful instructions or visuals on getting that fresh battery in properly. Let me know if you need any other sections added!

Special Considerations by Vehicle Make & Model

While most contemporary key fobs follow similar, straightforward battery replacement procedures, below are notable model-specific exceptions or guidance:

Toyota & Lexus Key Fobs

Must use a factory original or CR2032 equivalent replacement battery – other sizes won’t securely fit or make proper electrical contact.
The date code on the battery must be within 3 years for dynamic code models.
Match the numbers imprinted on the old battery’s flat contact side for proper dimensions and voltage.

Honda Key Fobs & Smart Entry Remotes

Replacement blade (flat) style key batteries only – coin types won’t align properly.
Recommend removing the battery gradually with fingernails vs. metal tools to avoid scratches.
Pry slot location differs between various Honda fob models – Check your owner’s manual diagram.
May require a multi-button reset sequence instead of the standard 30-second method.

Nissan Intelligent Keys

Nissan fobs use a specialty CR2025 battery – Remotes won’t function with CR2032.
Push-to-start button on the dash may blink fast indicating low low-key fob battery after replacement. Drive the vehicle to re-sync and stop the warning.

Hyundai Smart Key & Genesis Intelligent Key

Note the model number inside the case during disassembly to find specific instructions.
Must use a paper clip in the manual reset hole on the back side after swapping the battery.

Conclusion

Replacing the small battery inside modern high-tech wireless key fobs does not need to be difficult or expensive. This comprehensive DIY article walked through determining when a depleted battery requires replacement, exactly which tools/supplies to gather beforehand, stepwise installation guidelines, instructions for resetting and re-pairing the key fob with your vehicle computer, plus troubleshooting tips for common issues that may arise.

With this knowledge and a handy visual reference, you can feel totally confident tackling a dead key fob battery yourself quickly, safely, and cheaply. The most important takeaways are to work slowly & gently, avoid touching components inside the housing, check polarity multiple times before inserting any new battery, and properly snap back together both casing halves.

Make it a habit to proactively swap fresh batteries into all key fobs on your household or business key rings every 2-3 years. A little simple periodic maintenance lets you conveniently keep unlocking doors and starting your engine for years to come!