How to Program a Key Fob

If you have anything close to resembling a modern car the chances are you can at least unlock your car doors from several feet away at the touch of a button and open your trunk without even once putting a key into the lock.

We take this for granted in many ways and even when we have an actual key to do the unlocking if we really need it, let's be honest we resent the key fob remote buttons not working. In this post we will help you troubleshoot this issue and get you back to easy unlocking.

Wait, Is It the Battery?

When a key fob stops working never just assume it’s a reprogramming situation because just like all portable electronics the fob does need a power source and in this case this is a battery. This is why the first thing we have to do is see if changing the battery makes a difference.

Key fobs can vary so check with your owner's manual to see how to change the battery and also which battery you will need. Once you have done this test the key fob and if it is now working then you can stop there. If it is still not working you may need to reprogram the fob or even get a new one altogether.

The Programming Process

The process to reprogram a fob is not too complicated so here we will go through a step-by-step tutorial.

  1. Get into the driver's seat of your vehicle making sure you have all the keys with you that you need to program. Also, make sure to close all of the car doors as failing to do so may cause an issue.
  2. Now that you are sitting comfortably, insert your physical key into the ignition and turn it to the “On” position engaging the electrical systems in the process. You should not be in radio mode and the engine should not be running at this point.
  3. With the key still in the “On” position press the lock button on the key fob and turn the key back to “Off.” Repeat this at least three times and end the cycle with the key back in the “On” position. This should tell your car's electronic control modules that this is your key.
  4. Having completed the above process several times you should hear the lock sound of your car’s doors being unlocked. This indicates that the vehicle has entered programming mode and so far things are going just great.
  5. Finally, within five seconds of that door lock sign press the lock button on your key fob and this should complete the programming.

Additional Remotes

If you have other key fobs you want to program at the same time then you follow the steps as above but after hearing that final lock sign you just have to press the lock button on the key fob to be programmed within 10 secs.

How to Leave Programming Mode

Having programmed all your relevant key fobs you will want to end the programming mode. This is very simple to complete. All you need to do is turn the ignition back to the “Off” position and remove your key. The programming procedure will now have been terminated and you would have to restart the process to add additional key fobs.

Test Your Key Fobs

Having gone through the process, exit your vehicle and close all the doors. Test the lock and unlock functions on all of the fobs. If they all work then everything was a success. It is possible that only one will work or none may. At this point, you can run through the process again and if it still fails then this process does not work for your make and model of car.

It May Be More Difficult

If the solution above hasn’t worked out then your make and model may need a different programming solution. At this point, you may want to contact your authorized car dealer and ask them what you need to do.

This could be pricey to do so for older models you can perhaps look for information online that matches your exact make model and year of car. You might also contact a local locksmith or auto repair shop for advice.

What About Starting the Car?

So far what we have tried to do is reprogram the key fob to allow you to lock and unlock the doors. If your car has an immobilizer then this process will not automatically allow you to start the engine with the key.

Inside the part of the key you insert in the ignition is a small chip or transponder. If this does not send the right signal to the immobilizer the electronics may start but the engine will not. Programming this transponder then is harder and will require software.

You are unlikely to have this software at home so you may need to contact a dealer or a mechanic to help you with this. This could potentially cost between $200 - $500 depending on your make or model.

Why Do They Use a Transponder?

The thing that can make programming a key fob expensive is that pesky transponder but why is it important? Years ago you could start some cars by simply having a similar key because the locking systems were so simple.

It was a great time for thieves but things have advanced since then and now most new cars have a transponder in the key which communicates with the car's computer system. If the transponder sends the wrong signal then the engine does not start.

This is better for security purposes but can mean higher costs if you need a new key fob or the old one breaks.


The process for programming a key fob to allow you the ability to lock and unlock a car is really quite simple. However, due to car security advances it is harder to program a new key fob that will allow you to start the engine.

You will have to seek more professional help if you need to reprogram the key fob to allow you to start the engine. This is because it is a more complicated procedure that has to be done with an eye toward security.

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