How a Car Key Fob Works

Fob car keys are becoming more popular and common as they're often being used for cars with keyless entry, which is 80% of new cars in the UK. Due to the popularity of keyless entry systems for cars and the rise of fob car keys in the UK, we thought we'd tell you everything there is to know about fob keys in this Keytek® Auto Locksmith blog!

What is a Car Key Fob?

A fob car key is the small remote-control device that controls a remote keyless entry system for a car. The noise that comes out of your car keys when pressing the button and unlocking the car doors is all from the fob embedded into the key. It contains a short-range radio transmitter to send distinct codes to a receiver unit in the device.

How Does a Car Key Communicate with Your Car?

A car key fob is made to be used to secure your car and only give certain people access to your vehicle. They are digital keys that provide remote access, so you don't need to put the key in the car door to open it, as you do with manual locks.

Fob car keys work through their built-in Radio Frequency Identification system. The car itself has its own unique tags that the car key fob also has, so when the button on the fob is pressed, it communicates to the car that has the same tag information which in turn locks or unlocks the car.

Keyless Entry vs. Keyless Start

Keyless entry allows you to unlock your car without physically using the key. The security system can detect a signal from the key fob when you are in close proximity to the car and if you touch the handle or press a button, the doors will unlock automatically. The benefit of keyless entry is that you don’t need to fish your keys out of your bag, especially if you have your hands full.

Keyless start systems allow you to start the engine without inserting a key into the ignition. Once your fob is inside the vehicle, you normally push a start/stop button to start the engine. The benefit is like that of keyless entry, it means you don’t have to find your key to start the car.

What Happens When a Fob Stops Working?

There are a few common reasons why your keyless fob may have stopped working. It’s worth checking out these before thinking of replacing or calling a locksmith.

Dead Battery

This could be the case if your car won’t unlock when you touch the door handle, or the push button start won’t work or says not detected.

If you are in a rush to get somewhere you can just use your physical key to gain entry to the car. You can also try to hold the fob near the start button. Some vehicles have a back up system that can actually detect a weak or dead fob battery, if placed in close proximity to the start button.

The easiest and cheapest thing you can do to rectify the situation is to replace the battery in the fob. The majority of keyless entry fob have a simple ion cell battery.

Signal Interference or Damage

This is likely the case if your fob intermittently doesn’t work, or you’ve replaced the battery and you are still getting a ‘key not detected’ message when you try and start the car.

A signal interference could be because you live close to radio towers, security gates or other things that use radio waves to function. Or it could be because there is internal damage to the circuit.

If possible, you could try and move to a different location and try the key again or try your spare fob if it’s available. Worst comes to worst you’ll need to visit the dealership or contact a reputable auto locksmith to get them to reprogram the key.

It’s lost or completely dead

The keyless entry is not working at all, and you are unable to start the car via a keyless method.

Unfortunately, this is when you will definitely need to get in touch with an auto locksmith or your dealership to get a new fob or your current fob replaced.

Can You Replace or Reprogram a Key Fob?

You can absolutely replace and reprogram a key fob, although probably not yourself. There are a few ways that you can do this, with varying cost.

The Main Dealership

You can guarantee that the dealership for your car is going to be able to replace or reprogram your fob, with minimal fuss. They will offer the full service of key cutting and reprogramming etc. However, it’s likely that this will be the most expensive option, typically it’ll cost £150 minimum, and the cost will change depending on the make of your car. The dealership may take a few days to fix your issue if they need to order the key fob.

An Auto Locksmith

Auto locksmiths are typically cheaper than going to the main dealership and they offer a mobile service. However, an auto locksmith may not be able to work on high-end or encrypted system. Typically, an auto locksmith charges start anywhere from £80 depending on make of car and what needs doing. You will also be able to get the auto locksmith to come to your location on the same day, meaning you might be able to fix your issue quickly.

Aftermarket or Online Key Fobs

You can buy a blank or unprogrammed key fob on Amazon, eBay or a similar website, however you’ll still need a professional such as an auto locksmith or dealer to cut and program it. There are fobs you can find online that will pre-program for you, if you supply your car information. However, you take the risk of it not working when you order sight unseen online.

If you are in need of a new keyless car fob or any other auto locksmith services, don’t hesitate to call our experienced auto locksmith for a quote on 01202 830 625.