How to Program a Key Fob Yourself at Home (8 Easy Steps)

If your key fob suddenly stopped working it can be because it lost its programming data. Here is a step-to-step guide on how to reprogram key fobs without special tools

How To Program A Key Fob

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

Like any other electronic device, these key fobs may fail to function after some time, usually due to signal or data loss. Luckily, you can often easily reprogram the remote control yourself at home, to relearn the data.

In this article, we will explain step-by-step how you can program your car key fob so you don’t have to take it to a car dealer and waste your money. Let’s go!

How To Program a Key Fob

Different car models have different methods for key fob programming. The process mentioned below is the most common way to reprogram key fobs. This guide works with most car models on the market, but sometimes you need to find specific information for your car model.

You can find more specific information about your car’s remote control in a repair manual. Follow these steps to program a key fob at home:

  1. Replace the Key Fob Batteries

    Replace Car Battery Rotated

    Before doing anything else, replace the battery in the key fobs if you haven’t done so in a while. A bad key fob battery can give you a real headache while trying to reprogram it.

    The batteries for key fobs are often cheap and also easy to replace, so it’s definitely worth it to avoid issues. Check your owner’s manual or a repair manual if you don’t know how to replace them.

  2. Get inside the car

    Locking Car

    Get in the driver’s seat with your car keys and any remotes you want to reprogram and close all the doors. Closing the doors is very important, as leaving one open can disrupt the process.

  3. Turn on the ignition

    Ignition Lock

    Once seated, insert the key into the ignition and turn it to the ‘On’ position, so the electrical systems are powered. Make sure that the ignition is not in 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 a signal to your car’s electronic control modules that it is your key in the ignition that is sending the signal, and it saves the data afterward.

    RELATED: How to Unlock & Start a Car With a Dead Key Fob

  5. Listen for a Lock Sound

    Locked Car

    After repeating the above process, you will hear the lock sound, unlocking your car’s doors. This indicates that your car has entered the programming mode and the process is successful so far.

    When you hear the door lock sign, press the lock button on your key fob again within five seconds, and programming should succeed.

  6. Program Additional Remotes

    Key Fob Lock

    If there are additional remotes that you want to program to the car, press the ‘Lock’ button within 10 seconds after entering programming mode to program those remotes as well.

    You can also try to press the lock or unlock button at the same time as you program the primary remote when turning the ignition in the beginning to get a successful result.

  7. Turn off the ignition

    Key Fobs

    Once the above steps above are performed, and you got the successful signal for all the key fobs you wanted to program, turn the ignition back to the ‘Off’ position to terminate the programming procedure.

  8. Get out of the car and test the result

    Open Car

    Take all the key fobs you programmed with you and leave the vehicle and close all the doors. Test both the unlock and lock function with all of your key fobs that have been programmed to verify the functionality.

    If the key fobs still don’t work, or only one of the key fobs works that you tried to program, you may want to try the whole process one more time. However, there is always a risk that this method will not work on your car model.

Estimated Cost: 5 USD

https://www.youtube.com/watch?v=wfoD7WDsZbM

Specialist Hardware Required for key fob programming

For some cars, key fob programming may not be as easy as the steps above, and in these cars, special hardware and software may be required. In general, we suggest that you call your authorized car dealer for information on how to program the key fobs for your particular car model.

Because getting this information or help from an authorized dealer can be expensive and may not be worth it for older car models, you can also try contacting a locksmith or local auto repair shop.

RELATED: Lost Car Keys – Cost & Replacement Keys

Key Programming with Immobilizer

The information above is only for programming the key fobs to be able to unlock the doors to enter the car. If you want to program new keys to be able to start the car engine, the process is usually much more difficult, and nothing you can do at home without the right tools.

This is due to the fact that all modern cars have an immobilizer system. Even if you copy the original key and reprogram the key fob to match the new key, you will not be able to start the car engine with that key without a successful reprogramming procedure.

Inside the car keys is a small chip or transponder that sends a signal to the immobilizer system in your car. If this signal is not correct, the engine control module will not allow the engine to start.

Therefore, you need to program the immobilizer to match the transponder chip in the new car key and unfortunately this programming requires special software, usually directly from an authorized dealer depending on the car model.

There are also locksmiths who can access this information and reprogram the immobilizer for you, which can be a little cheaper.

READ MORE: How to Program Transponder Key Without the Original

Understanding Vehicle Security

Car security can be divided into two categories – Car Entry and Starting the Car. In most modern cars, you don’t need to insert keys to open the doors because they have remote locking/unlocking. The older remote car entry systems used RF systems which were not completely secure as their signal could easily be intercepted and replayed 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 these 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.

Transponder Function

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.

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.

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

RELATED: 5 Signs of a Bad Immobilizer or Transponder Key (& Replacement Cost)

Frequently Asked Questions

Can you program a new key fob yourself?

If it’s just the key fob itself to unlock and lock the car you want to program, you can usually program it yourself. However, it is impossible to program a key for the start function without the right tools on most modern car models.

How much does it cost to reprogram a key fob?

Reprogramming a key fob for the lock and unlock function 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 of the time, to program the key fob push start, you need the right diagnostic tools because of the immobilizer, which only authorized dealers usually have access to. However, if you just want to reprogram the unlock and lock function, the program method is the same as a standard key fob.

How to erase key fob memory?

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

Can you program a key fob without going to the dealership?

Yes, you can program the unlocking and locking function of the key fob without going to the dealership. But if you need to program the transponder to be able to start the car with the key – you may need to go to the dealership or a locksmith.

Does a key fob have to be reprogrammed after replacing the battery?

Usually, key fobs will not lose the memory just because you changed the battery. If the key fob does not work after the battery change, it may be because you installed the battery incorrectly. However, some car models’ key fobs may lose memory when you remove the battery, but this is quite rare.

Conclusion: Key Fob Programming

To program a key fob in most car models, you should insert the key into the ignition, press and hold the lock or unlock button on the key, cycle the ignition 2-3 times while holding the button. Listen for a lock sound and then remove the key and get out of the car to test the results.

Car key programming can be quite a complex subject, but with some quick research and basic knowledge, you should be able to understand the basic function of the system. Programming a key fob for the central lock system is usually a fairly simple task, but if you want to program an immobilizer, you may need to contact a professional.

I hope this guide helped you to either program your key fobs or taught you a little about what to do when you have problems with your key fob.

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Magnus Sellén
Written by:

Magnus is the owner and main author of Mechanicbase. He has been working as a car mechanic for over 10 years, and the majority of them specialized in advanced car diagnostics and troubleshooting. Certified Automotive Diagnostic Technician.