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How To Change the Battery in Your Car’s Key Fob

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Is your car’s key fob not responding? There could either be something wrong with the internal electrical system or with your battery! If it’s the latter, this post will tell you how to change the battery in your car’s key fob.

We’ve all been in this situation: you approach your parked car, ready to drive away to your next destination, and rummage for the key in your pocket. However, imagine your surprise when pressing the familiar unlock button yields no response! You try and try again to no avail, ultimately deciding that something must be wrong with the key fob.

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While there are several issues that could create such problems, a dead battery is the most common culprit. This post answers everything you need to know about changing the battery in your car’s key fob.

What is a key fob?

A key fob – sometimes called a remote keyless system – is a handheld device that allows you to lock and unlock your vehicle remotely. It consists of a remote control and RFID antenna that is connected to your car’s locking system. Some key fobs have a retractable physical key with which you can lock/unlock your car manually as well.

What happens when the key fob battery is low?

Typically, a key fob with a low battery starts exhibiting some or all of the following symptoms:

  • The fob may become less responsive or unresponsive over time.
  • It may not lock/unlock your car easily and may start losing its range. You may have to get closer for the keyless entry function to work.
  • In cars with a push-button start, the car may not recognize a key fob when the battery is weak

How long do key fob batteries last?

Most key fob batteries last for around three to four years with regular usage.

Can you unlock your car with a dead key fob?

Yes! Having a dead battery in your car key fob does not mean that you are left stranded. Car manufacturers have foreseen this situation and built-in fail-safes to ensure you can unlock your car even in such a situation.

Here’s what you should do:

  • All car manufacturers include a mechanical key in the car’s key fob. This can be accessed by sliding/pressing a small button usually located on the side of the key fob, which will remove the fob cover.
  • Once you get the mechanical key out of the fob, insert it into the key slot and turn it to unlock/lock your car.

Mechanical keys are usually included in the key fobs of all major car manufacturers like Honda, Kia, Toyota, Mercedes, Ford, etc.

Also read: All you need to know about car key replacement

Can you drive with a dead key fob?

No auto manufacturer is going to pin everything on the key fob working all the time. Therefore, even if your battery dies, you can still use the fob to drive the car.

  • Despite most cars going keyless, several of them still have a key slot – usually located on the steering column. It will typically be covered by a plastic cover which you can pop off. Once you insert the physical key into it, you can easily turn on the car and drive away.
  • Some cars begin ignition with the START button, which switches on the car only if the key is detected. With a dead battery, the car may not recognize the key fob and hence the START button may be unresponsive. In such cases, you can use the fob itself to push the START button, which will switch on the car.
  • Some vehicles like Fords have a slot on the steering column where you can insert the fob, which will start the vehicle.

Can you replace a key fob battery yourself?

How to change the battery on your car key fob

You can replace the battery in your key fob by following these steps:

  1. Find out the type of battery used: This will be embossed on the side of the fob. The most commonly used type of battery is button cells, sold by brands like Duracell and Energizer.
  2. Open the key fob at the seam: Most key fobs are made of two halves that join together at a seam. You can easily split them apart by using a finger or sharp edge against the notch.
  3. Take out the old battery and replace it with a new one: The button cell battery will look like a little silver coin. Pop out the old one and pop in the new one the same way. Take care to insert it in the same orientation (positive and negative ends).
  4. Snap the fob halves back in place and test it: Check whether the lock/unlock and start functions are working properly to ensure you’ve replaced the battery correctly.

Do I need to reprogram the key fob after changing the battery?

Typically, you do not need to reprogram the key fob after changing the battery. However, if you’ve replaced not just the batteries but also some of the internal wiring and electronics, you may need to reprogram it by pairing it with your vehicle once again.

The usual sequence for reprogramming your car battery is as follows:

  • Put the key into the ignition
  • Turn the key into the ON position (which switches on the instruments and screens but not the ignition) and then turn it back to the LOCK position.
  • Do this several times until you hear a chiming sound (or some other sound indicating a reset)
  • Press the lock and unlock position on your key fob to reprogram it. This should ensure the correct functions are saved and that the vehicle will respond the next time you use it.

What kind of battery does the key fob take?

Key fobs use 3V button cell batteries – usually the CR2032. Other button cell batteries that are commonly used include CR2016, CR1616, CR2025, and CR2450. Popular brands that sell these batteries include Duracell, Energizer, and Panasonic.

How much does a key fob battery cost?

A button-cell battery pack can cost you between $2-5 depending on the brand and number of batteries you buy. For example, an Energizer pack of two costs $2, while a Panasonic pack of four costs $3.75.

Frequently Asked Questions (FAQ)

How to change the battery of a Honda key fob?

To replace the battery of a Honda key fob, ensure you first buy a replacement CR2025 battery. It will cost you between $2-4 dollars for a pair of batteries.

  • Slide the button to release the physical key
  • Pry the key fob open into two halves using a finger or screwdriver at the seams
  • Pop out the old battery and replace it with the new one
  • Take care to insert the new battery in the same orientation as before, with the correct (+) and (-) signs in place.
  • Test the battery for any issues¬† and ensure it is in proper working condition

Does the key fob battery face up or down? 

Most key fobs have the battery placed with the positive (+) side facing up toward the buttons. You can use the screwdriver as a pry bar to open either key FOB style. Put in a fresh battery. Place it with the positive terminal facing upward like the old battery. Flipping the battery will prevent the key FOB from functioning. However, it is always best to consult the user manual of your specific key fob to ensure proper battery installation. 

Can I still start my car without the key fob? 

Yes, you can start your car without the key fob, depending on your vehicle’s specific make, model, and year. In modern cars, keyless entry systems are designed to prevent the engine from starting without a properly programmed key fob.¬† If your car has a keyless ignition system (push-button start), it typically requires the key fob’s presence and authentication for the engine to start.¬†

Will a dead key fob cause a car to not start?

No, you can start your car even if the key fob has a dead battery. You can either use the mechanical key stored in the fob or start the car by pressing the START button with the key fob.



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