How To Program a Key Fob

Modern cars today come with electronic car keys (also called key fobs) that come with several different features.

You can use it to remotely start your vehicle, lock and unlock the car door, set up the alarm, and open up the trunk. These handy devices have replaced traditional car keys and made things even more convenient from an accessibility perspective.

But just like any other electronic device, a key fob can malfunction and it can prove problematic if you don’t know how to fix it.

Thankfully, you can easily reprogram your car’s key fob to ensure it transmits coded signals to the vehicle’s receiver unit.

This step-by-step guide will explain how to reprogram an electronic car key so you can confidently do it right at home.

The basics of reprogramming a key fob

Different cars have different ways of reprogramming their key fobs. In general, the process we’ll discuss is usually effective for about 90% of cars out on the market.

If for example, you own a luxury car or a high-performance vehicle, we recommend you take it to an auto dealership because these car keys can be very expensive to replace.

You can find more information about your vehicle’s key fob by reading the owner’s manual. Here are the basics of reprogramming a key fob:

  1. Replace the batteries

Key fobs operate on batteries and if you’ve been using your car for more than four years, it’s a good idea to replace the batteries first.

Doing so will help avoid unnecessary headaches during the reprogramming process. Batteries are quite cheap and it only takes a matter of minutes to replace them.

Check your owner’s manual for instructions on replacing your car key’s batteries.

  1. Get inside the car

Get inside the car with the key fob in your pocket. Make sure all the doors are closed as leaving car doors open can interfere with the reprogramming process.

  1. Turn on the vehicle

Turn on your car by inserting the keys and switching it to the ‘on’ position. This powers all the electrical systems in your vehicle.

Check to make sure the ignition is not in radio mode and do not start the engine while reprogramming.

  1. Press the lock button

While the key is in the on position, press the lock button on the fob whilst turning the key to the off position simultaneously.

Do this three times and finish with the key in the on position.

What this does is send an indicator to your car’s ECU that it’s your key in the ignition that’s sending out signals to save data afterwards.

5. Wait for a lock sound

Once you’ve completed the above process, wait until you hear a lock sound.

This is an indicator that you’re now in programming mode.

To continue, press the lock button again within 5 seconds to complete the programming.

6. Programming additional remote

You can also program any additional remote by simply pressing the Lock button within 10 seconds after entering programming mode.

7. Turn off the ignition

After the above steps are completed, you can now turn off the ignition to end the programming procedure.

8. Test out the result

With your key fob in your hand, step out of the vehicle and close all doors. Test both unlocks with your key fob that got programmed to confirm if it’s working or not.

In some instances, the programming procedure we discussed may not work. If it doesn’t, then you’ll need specialist hardware designed for reprogramming key fobs.

The first option is to contact your authorised car dealer to address the situation, but this can prove very expensive if you go this route.

If budget is a concern for you, we recommend having your car remote key re-encoded by an auto locksmith company or a mechanic workshop for a fraction of the cost.

You can also request for a separate master key if you so choose.

How vehicle security works

Your vehicle’s security operates in two ways and that is car entry and starting the engine.

Most modern cars today no longer need keys to open the doors since they use remote locking/unlocking to do that.

Back in the day, older car entry systems used RF systems which can easily be hijacked by capturing the signals and playing them back to unlock the car. 

Thankfully, car entry systems have evolved and the cars of today use a more sophisticated rolling code system which generates a new code every time, thus making it impossible for thieves to replicate those codes.

The receiver unit on the vehicle produces the same code as the entry locks to ensure both devices are synchronized perfectly.

Some European manufacturers used infrared systems that work by pointing the remote towards the car to unlock the doors but these have become less common nowadays.

In regards to starting the vehicle, older cars (1990 models and below) used a simple key locking system which made it easier for thieves to get the engine going.

However, newer cars came equipped with ECU technology as well as a transponder for improved security.

Luxury vehicles have better security compared to normal cars since the car entry system can be coded according to the driver’s specifications.

For example, a Rolls-Royce has a memory function that automatically adjusts the seats, mirrors, and steering wheel angle as the driver inserts the key.

As technology evolves, manufacturers are looking for more secure ways of entering/staring a vehicle, with one example being a fingerprint recognition system.

Instead of push-button start, the driver can start the car and fire up the engine with his fingerprint.

Modern cars have yet to implement this system but it sure looks like cars of the future will be adopting these technologies once manufacturers nail it down.

Understanding how a transponder works

You may have heard of a transponder as part of your car’s entry system.

But what is it and how exactly does it work? A transponder (also called a chip key) is a device that picks up an incoming signal and responds to it automatically.

As the key is inserted into the ignition, the transponder is activated by the radio frequency signal coming from the ignition barrel.

So how does a transponder work exactly? Most car transponders follow the same process for key identification.

An induction coil is mounted to the ignition lock which generates an electromagnetic field once a key is inserted.

The energy from that electromagnetic field is absorbed by the key windings and use it to power the transponder chip, thus emitting a code signal to the ECU.

The signal is interpreted by the ECU in an alphanumeric code which then powers up the car’s electrical components and starts the engine.

While modern car key entry systems have made our cars more convenient and secure, they do require a fair bit of knowledge and experience to repair.

Knowing how to reprogram your key fob is a great way to know more about your car and save money as well during the whole process.

Follow this guide when reprogramming your key fob and it should be functioning properly after you’re finished.


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