Key fob not working? Here’s what to do

Key fob not working? Here’s what to do
Modern technology has dramatically changed the automotive sector over the past few decades – and one of the most common items is the car key fob.

Replacing the traditional key to enter a vehicle, these fobs are available with almost all makes and models of cars available in the UK today.

This guide looks at what issues they may have and how to fix them.

What is a car key fob?

A key fob is a small electronic device that is used to remotely control functions on a vehicle.

This includes locking and unlocking the doors, opening the boot, and sometimes even starting the engine.

Some also have other buttons that allow a car to flash its lights, so the driver can find their vehicle in a crowded car park.

Key fobs use radio frequency identification (RFID) or infrared signals to send commands to the vehicle’s on-board computer.

Some car key fobs have a physical key attached or built into the housing for the device. They will also have space for a keyring to add other keys and items.

Benefits of a key fob

Traditionally cars have always used keys and a lock that the driver turns to both enter the car and start the engine.

Since the introduction of stop/start engines, there has also been the use of key fobs to unlock the doors and boot.

There are many advantages to using a fob over a key:

  • Security: Many copied car keys can be unreliable and easily lost or stolen. However, due to fobs having an RFID chip installed – they can only be used to open one vehicle. If it is stolen, then a driver can contact the manufacturer to deactivate the key remotely.
  • Smaller size: Due to having multiple buttons on a small handheld device, it is easier to fit in a pocket or bag.
  • Reliability and durability: Due to their size and quality of the technology used they are designed to last the lifetime of the vehicle. Sometimes a battery may need to be replaced.
  • Reprogrammable: If you want to have the fob reprogrammed for added security, this can be easily done by the manufacturer.
  • Convenience: Drivers can easily access their vehicle or unlock it for passengers before they reach the vehicle. It can also remotely open the boot, and flash the lights if you are looking for the vehicle in a car park.

With almost every car on the market today coming with a key fob, it is unsurprising that there are a lot more advantages to owning one.

If you buy a car, then you will likely be given a pair of key fobs that work with your vehicle.

Why is my car key fob not working?

There are several reasons why your car key fob is no longer working properly. Before looking for a replacement or a new battery, make sure you are not too far away from your vehicle or trying to unlock it from inside the house.

Here are some examples:


The most common issue is the battery running out of charge and needing to be replaced.

In most cases, a car key fob will last many years, but if it is used more frequently then you could end up having to buy one.

This can easily be done at a local garage, tech shop or by yourself at home.


If a driver has dropped or damages the fob, battery, or housing, then it could lead to it not working.

This is common if the fob has been dropped in water.


Sometimes a key fob can develop faults, and the only way to fix it is to take it to the manufacturer to have it reprogrammed.

If you need to do this, remember to take your spare set to have that version also updated with the latest information.

Radio interference

Although this is only likely in older car key fobs, if there is a lot of electrical or radio interference, then it could cause issues with the fob.

The only way to resolve this is to try and unlock the vehicle from a different position.

This is often what car thieves do to access a vehicle.

Car key fob replacement

If you have lost your car key fob – or it has been stolen – then you will need to have it replaced.

Car owners will need to purchase this from a dealership, where you will need to provide all your details and proof of ownership.

The new fobs will need to be programmed to your vehicle. If the vehicle also has a physical key, then this will also need to be cut.

Following this, the fob will need to be tested before you are allowed to driver the vehicle home.

This process can vary slightly in some makes and models of vehicle.

A new car key fob can cost from £250 to well over £1000. This includes the fob itself as well as any other work that is carried out.

Key fob battery replacement

If your car key fob battery has died, then replacing it with a new one is a simple task that can be done at a local garage, shop or by yourself.

Car key fobs are held together with small screws that you will need to remove to get the battery out of the housing.

There will be a release button to get the battery out and where the new one will slot into place.

The battery itself will have a number that starts with CR. This is the type of battery you will need to purchase.

New car key fob batteries will cost between £5 and £10, and can be purchased in most shops and garages.

Like other types of battery, make sure you make up the positive and negative polarity before closing the housing and putting the screws back into place.

Test the fob, and if it is all working, then you are good to go.

If not, then it might be worth visiting your local garage to see if there are any other issues.

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