how to change a key fob battery

Electronic car keys, also called key fobs, are useful in controlling your car's doors, trunk, and alarm, and can even remotely start your car from a distance.

Like any other electronic device, these key fobs can malfunction after some time, typically due to signal loss. However, in such a case, you can easily reprogram the remote yourself so you can still use it.

This article, will explain step-by-step how you can program your car key fob so you don't have to take it to an auto-dealer and spend your precious money.

How to program a key fob

Different car models have different ways to program their key fobs. The process mentioned below is the simplest way to reprogram any remote in general. This guide works with most car models on the market, but sometimes you need to find special information for your car model. You can find more specific information about your car's remote in the owner's manual. Follow these steps to program a key fob at home:

1. Replace the batteries inside the key fobs

Replace Car Battery Rotated

Before doing anything else, replace the battery in the key fob/s if you haven't done so for a while. A bad key fob battery can give you a real headache while you are trying to reprogram it. The batteries are often cheap and also easy to replace. Check your owner's manual if you do not know how to replace them.

2. Get inside the car

Locking Car

Get in the driver's seat with your car keys and the remote and close all the doors. Closing the doors is very important, as it may disturb the process if you leave one open.

3. Turn on the ignition

Ignition Lock

Once seated, insert the key into the ignition and turn to the 'On' position so the electrical systems are powered. Make sure that the ignition is not in the radio mode, and do not start the engine.

4. Press the lock button on the remote key

Locking

With the key in the 'On' position, press the fob's lock button and turn the key back to the 'Off' position. Repeat this process at least three times, ending the cycle with the key in the 'On' position. This sends an indicator to your electronic control units that it's your key in the ignition sending out the signal, and it does save the data afterward.
RELATED: How to Unlock & Start a Car With a Dead Key Fob

5. Listen for a Lock Sound

Locked Car

Once you have repeated the above process, you will hear the lock sound. This indicates that you have entered the programming mode. Once this is done, press the lock button again within five seconds, and the programming will succeed.

6. Programming additional remotes

Key Fob Lock

If there are additional remotes, press the 'Lock' button within 10 seconds after you enter the programming mode to program those remotes as well successfully.

7. Turn off the ignition

Key Fobs

Once the above steps are performed, turn the ignition back to the 'Off' position to terminate the programming procedure.

8. Step out from your car and test the result

Open Car

Take your key fobs with you and leave the vehicle and close all doors. Test to both unlocks with all your key fobs that got programmed to verify the function.

Estimated Cost: 5 USD

Specialist Hardware Required for key fob programming

For some cars, key fob programming may not be easy, and in that car, specialist hardware may be required. Typically, we would suggest that you call your authorized car dealer, but this can be expensive.

You can have yourcar remote key re-encoded from any other auto locksmith company or a mechanic workshop for a comparatively lower price and have a separate master key made.

Creating a new master key may require a code card which can be found in your car's manual.

RELATED: Lost Car Keys – Cost & Replacement Keys

Understanding Vehicle Security

Car security can be divided into two categories – Car entry and Starting the car.

In most modern cars, you do not have to insert keys to open the doors since they have remote locking/unlocking. The older car remote entry systems used RF systems not fully secure as their signal could be easily captured and played back to unlock and enter the vehicle.

The modern entry locks use a more sophisticated rolling code system that generates a new code every time. The receiver on the vehicle also produces the same code, so both the electronic devices are synchronized. Infrared systems were also used by some European manufacturers who required pointing the remote towards the car to unlock. Still, most have been replaced with RF technology now.

Talking about starting the vehicle, traditional cars had a simple key lock system that could be unlocked from any similar key. This was convenient for thieves as it allowed them to drive away with any car easily. However, new cars have ECU technology and a transponder for added security.

Luxury vehicles can be coded according to the driver's specifications. For instance, vehicles such as Rolls-Royce have a memory function, and as long as the driver inserts the key, the seats, headrest, mirrors, and steering wheel are adjusted according to the driver's settings.

Manufacturers are now working towards removing the need for the key altogether and adding a fingerprint recognition system.

What is a Transponder?

Transponder technology is now apparent in many areas that require security access and are now popular in modern automobiles. New vehicle keys now feature a transponder chip, and as the key is inserted into the ignition, the chip is triggered by the radio frequency signal sent from the ignition barrel.

The chip then transmits a signal to the car's ECU, which, when found to be correct, disables the immobilizer and starts the engine.

Can you program a new key fob yourself?

If it is only the key fob itself to unlock the car, you can most often program it yourself. However, programming a key for the start function is impossible without the right tools.

How much does it cost to reprogram a key fob?

Reprogramming a key fob for the lock and unlock costs nothing if you do it yourself in most car models. However, if you need to program the immobilizer function, you can expect a total cost of 200$ to 500$ for reprogramming at a workshop.

How to program key fob push start?

Most often, to program key fob push-starts, you need the right diagnostic tools because of the immobilizer, which only the authorized dealers have access to. If you just want to reprogram the unlock and lock feature, the method is the same as a standard key though; you just need to learn how to switch on the ignition properly.

How to erase key fob memory?

To erase the key fob memory, you need to use a suitable OBD2 diagnostic tool. Not all general scanner tools can do this, and you most often require a specific tool for your car model.