Ever walked up to your car while pressing the unlock button, only to find your key fob isn’t working? If so, you’ve experienced the kind of frustration that’s just key to ruining your day.
In keyless entry system cars, a key fob performs crucial functions like unlocking the car door and starting the engine. However, it can fail for several reasons, ranging from a dead key fob battery to signal blockage.
Keep reading as we explore the nine possible causes of a key fob not working and provide simple solutions to help you get back in your car.
This Article Contains:
9 Common Causes of Key Fob Not Working and Solutions
Here’s a look at the possible causes of car key fob failure and how to fix them:
1. Dead Key Fob Battery
Most key fobs run on long-lasting lithium batteries; however, they can eventually lose power and need replacement. If your key fob isn’t working, a dead battery is likely the cause.
Solution: Use a spare key to unlock the car. If you don’t have one, simply replace the key fob battery. Here’s how:
- Look for a small opening on the fob and use a flat tool such as a coin or flathead screwdriver to pop it open.
- Take out the old battery and check its size and type (you can usually find this info in your owner’s manual). Install a new key fob battery with the same specs as the older one by correctly placing the positive (+) and negative (-) sides.
- After replacing the battery, test the key fob to see if it works.
If you can’t figure out which battery type to install or are having trouble opening the key fob, visit your nearest auto store, and they’ll replace the battery for you.
2. Faulty Battery Contacts Inside the Key Fob
With time, the metal connectors inside the key fob can become loose or damaged, disrupting its connection with the battery and resulting in key fob failure.
Solution: Open the key fob and check the battery terminals. If they feel loose or unstable, you can repair them by soldering the contacts back in place. However, if the damage is too extensive, get a new fob.
3. Key Fob Needs Reprogramming
A key fob must stay connected to your car’s receiver (a device inside the vehicle that receives signals from the key fob) to unlock and start the car. But sometimes, due to low battery or physical impact, the key fob can lose its pairing with the receiver and stop working.
Solution: Since this is a complex issue, it’s a good idea to have a local locksmith reprogram the key. The process usually varies by car model and involves pressing a combination of key fob buttons in a sequence while the key is in the ignition.
4. Damaged Key Fob Transmitter or Receiver
Key fobs work by sending signals to your car’s receiver, which controls the locking mechanism. If the transmitter inside the key fob or the receiver in the car is damaged, the key fob won’t function properly.
Solution: If there’s an issue with your key fob’s transmitter or the car’s receiver, a mechanic or professional locksmith will inspect and replace the faulty part.
5. Signal Interference
Sometimes, nearby electronic devices, such as cell phones and Wi-Fi routers, or strong signals from cell towers can prevent your key fob from opening the car door lock.
Solution: Keep your key fob away from electronic devices like phones, tablets, and laptops, as they can interfere with its signal. Moreover, avoid parking near tall buildings to prevent signal blockage.
6. Broken or Stuck Key Fob Button
Over time, the buttons on a key fob can wear out, become stuck, or break internally. If the rubberized buttons don’t pop back out or get jammed, the key fob won’t be able to operate the car door lock.
Solution: Open the fob and inspect each key fob button for damage. If they’re stuck, gently clean the area and press the buttons a few times to loosen them up. Then, reassemble the fob and press the unlock button. If it’s still not working, you need a key fob replacement.
7. Water Damage
If your car key fob comes in contact with water, it can experience two major issues — a short circuit or corrosion. While a short circuit will instantly stop the key fob from working, corrosion can build up over time and permanently damage the internal circuit board.
Solution: If it’s a minor spill, open the key fob and let it dry completely. But if the circuit board is blown or corroded, you’ll have to use the spare key fob or get a new key fob.
8. Faulty Engine Immobilizer
An engine immobilizer is an anti-theft device that prevents the car from starting unless it detects the correct car key fob. If the immobilizer system doesn’t recognize the fob due to a malfunction in the immobilizer itself, the engine won’t start.
Solution: If the immobilizer is faulty, use a manual key to unlock your car door. Next, you’ll need to reset the immobilizer to start the engine. This involves disconnecting and reconnecting the car battery and then trying to start the car. If this doesn’t resolve the issue, visit a mechanic for a thorough diagnosis and repair.
9. Dead Car Battery
A dead car battery can prevent your key fob from working, as the fob relies on the car’s electrical system to operate the locking mechanism and start the engine.
Solution: Most key fobs contain a hidden physical key to unlock the car manually. But if there’s no visible keyhole where you can insert your manual key, remove the plastic cover on the car door handle to access it.
While the physical key will help you unlock the vehicle, you’ll still need to jump-start the dead battery because the start button won’t work. Once your car is running, it’s a good idea to visit a mechanic for a battery replacement.
Want to know more about key fobs?
Keep reading.
3 FAQs about Key Fobs
Here are answers to some common queries you may have about key fobs:
1. What Type of Batteries Does a Key Fob Need?
Most remote key fobs require thin, coin-shaped batteries like the CR2025 or CR2032, but some may require smaller ones like the CR1632 or CR1620. These numbers represent the battery’s dimensions — specifically the diameter and thickness (measured in millimeters).
NOTE: Your owner’s manual will contain information about the battery type your key fob requires, or you can take your old battery to an auto parts store for the right match.
2. How Much Does It Cost to Fix Key Fob Problems?
Here’s what you can anticipate spending on car key fob issue repairs:
- Key fob replacement: $50 to $500
- Key fob reprogramming: $50 to $300
- Car battery replacement: $185 to $400
- Immobilizer repair: $200 to $1,000
3. What Can You Do to Avoid Key Fob Failures in the Future?
Follow these tips to prevent your car key fob from failing:
- Install a new fob battery every year or two, even if it’s still working, to avoid unexpected failure.
- Keep your key fob dry and protect it from exposure to water or moisture (rain or accidental washing).
- Avoid dropping, tossing, or stepping on your key fob to prevent internal damage.
- Store your current and spare key fob away from electronic devices like phones or Wi-Fi routers to prevent signal interference.
Fix Your Key Fob to Avoid Getting Locked Out
In vehicles with a keyless entry system, even a minor key fob issue can lock you out of your car. The good news is that while a key fob malfunction can be inconvenient, it’s usually easy to fix.
However, if the problem is caused by a dead car battery and getting to a repair shop seems impossible, let AutoNation Mobile Service come to you.
We’re a mobile car repair solution that offers easy online booking and a 12-month, 12,000-mile warranty on all services, including battery replacement.
Contact us for professional assistance and hassle-free repairs right from your driveway.