How Keyless Car Theft Happens and How to Stop It
Keyless car theft happens when a device fools the car into reading its key as close by, and it is stopped by blocking the signal of the key, adding a physical lock and adding a second immobiliser.
Inta-Lock Car Key Guides. Updated October 2026.
The police name the method relay theft. The key stays inside the home, the car unlocks and starts on the drive, and no lock is forced. Three other methods sit beside it, which are a jammed lock command, a key programmed through the diagnostic port and the theft of the key itself.
No single measure answers every method, so keyless theft prevention works in layers. A signal blocking pouch answers the relay attack, a hand on the door handle answers the jammer, a steering wheel lock adds a physical barrier, and a second immobiliser keeps the car from being driven after the doors are open.
How Does Keyless Car Theft Happen?
Keyless car theft happens when a thief uses a device to fool the car into reading its key as close by, so the car unlocks and starts while the key lies inside the home.
A car with keyless entry unlocks automatically when its key comes within a short distance. The system measures nothing except the presence of that signal, so a signal that arrives by another route is accepted in the same way.
Police guidance calls this relay theft. The thief stands within a few metres of the key, which sits on a hallway table or a kitchen worktop, and the car on the drive receives the signal as though the key were beside the door.
No lock is forced and no glass is broken. The key never leaves the house, which is why the first sign of a relay theft is an empty drive with every key still in the home.
Which Methods Do Thieves Use on Keyless Cars?
Four methods are used against keyless cars, and each one acts on a different part of the system, so each one has a different answer.
| Theft method | What the thief acts on | What the driver notices | What answers it |
|---|---|---|---|
| Relay attack | The radio signal of a keyless key that lies inside the home | Nothing at the time. The car is gone and every key is still in the house | A signal blocking pouch, the wireless signal of the fob switched off, and keys kept away from doors and windows |
| Signal jamming | The lock command sent from the key as the driver walks away | The car stays unlocked after the button is pressed | A hand on the door handle before the driver walks away |
| Key programming through the diagnostic port | The diagnostic port inside the cabin, once a door is open | The car is gone, and the keys of the owner are all accounted for | A lockable cover on the port, and a second immobiliser that works independently of the port |
| Theft of the key itself | The key, taken from a hallway, a bag or a pocket | A missing key, and then a missing car | Keys kept out of view and away from the front door, and the missing key removed from the car afterwards |
The relay attack is the method the phrase keyless theft usually names. The other three rows explain why a pouch alone leaves a keyless car exposed, and why the measures below are used together.
How Do You Stop Keyless Car Theft?
Eight measures stop or slow keyless car theft, and they work as layers, because each one answers a different method.
- A signal blocking pouch. The key and the spare key sit in a signal blocking pouch whenever they are not in use. Police guidance is to check every few months that the pouch still works.
- Keys away from doors and windows. Keys are kept out of view at home, away from the front door, the windows and the car itself.
- The wireless signal of the fob switched off. Some keyless fobs allow the wireless signal to be switched off when the key is not in use. The handbook of the car states whether the fob has the function and how it is used.
- A locked car, checked by hand. The door handle is tried before the driver walks away. Police guidance states that electronic devices are used to jam the signal that locks the car, and a door that opens shows a car that has not locked.
- A steering wheel lock. A steering wheel lock, a pedal box or a gear stick lock is a physical barrier that a radio device does not open. Police guidance points to security rated products.
- A cover on the diagnostic port. A lockable cover closes the diagnostic port, which on many modern vehicles gives access to the systems that unlock and start the car.
- Parking close to the home. The car goes in a garage overnight where there is one, and close to the home where there is not.
- An alarm, a tracker and a second immobiliser. Thatcham Research advises a certified alarm, immobiliser and tracking system. The alarm draws attention, the tracker helps to trace the car, and the immobiliser keeps the keyless car from being driven.
The first seven measures follow the police guidance on preventing car and vehicle theft, which sets out keyless entry as its own part of keeping the keys safe.
A keyless car in Leicester or Leicestershire with no second immobiliser? Matt fits the Autowatch Ghost 2, and a quote is agreed before work begins.
Call Matt on 0116 442 2084Does a Signal Blocking Pouch Stop a Relay Attack?
Yes, a working signal blocking pouch stops a relay attack on the key inside it, because the pouch screens the signal of the key from the device outside the home.
Police guidance is to put the keys in a screened or signal blocking pouch and to check every few months that the pouch is still working. A pouch that no longer screens the signal leaves the keyless key open to the relay attack again.
The pouch has three limits. A pouch does not stay working for ever, which is the reason police guidance sets the check every few months. A spare key left in a drawer still sends its signal. A pouch answers the relay attack only, so a jammed lock command, the diagnostic port and a stolen key are untouched by it.
Do Car Makers Protect Keyless Keys Against Relay Attack?
Yes, many car makers now supply countermeasures against the relay attack with new keyless cars, and the motion sensor fob is the example Thatcham Research names.
Thatcham Research states that cars with passive keyless entry and start are the ones exposed to the relay attack, and that many car makers now offer countermeasures such as motion sensor fobs. The statement sits within its Thatcham Research guidance on car security.
The protection differs between makes, models and years. The handbook of the car or the maker confirms what a given keyless key carries. An older keyless car with no countermeasure relies on the pouch, the physical lock and the second immobiliser.
What Does a Second Immobiliser Change?
A second immobiliser changes what happens after the car is unlocked, because the car is not driven away until a further step known to the driver is completed.
The factory immobiliser releases the engine when it reads a key it recognises. A relay attack presents the signal of the real key, so the factory system reads a recognised key and the keyless car starts.
A second immobiliser asks for something the key does not hold. Inta-Lock fits the Autowatch Ghost 2, which keeps a vehicle from being driven until a disarm sequence is entered on buttons the vehicle already has. The sequence adds no fob and sends no radio signal. Autowatch publishes Ghost 2 as protection against key cloning and relay theft, and as operating independently of the diagnostic port.
Ghost 2 is an immobiliser and nothing more. It does not sound an alarm, it does not track the vehicle, it does not lock the doors and it does not stop a vehicle being lifted or towed away. The fitting, the disarm sequence and the compatibility check are set out under Autowatch Ghost 2 immobiliser fitting in Leicester.
How Common Is Keyless Car Theft in the UK?
An offender manipulated the signal from a remote locking device in 40 per cent of thefts of vehicles in the Crime Survey for England and Wales for 2022 to 2023.
The figure is published in the government statement on vehicle theft equipment of 24 February 2025, which names keyless repeaters and signal amplifiers among the devices used. It covers England and Wales as a whole. No keyless theft figure for Leicester or Leicestershire is held, and none is given here.
The law on the devices is changing as well. The Crime and Policing Act 2026 sets out offences of possessing, importing, making, adapting, supplying or offering to supply an electronic device for use in vehicle theft. Each offence applies only from the date on which its provision is brought into force. The official legislation website showed the provisions as prospective, which means not yet in force, when this article was updated in October 2026. The maximum penalty in the Act is five years imprisonment, an unlimited fine, or both. Signal jammers and signal amplifiers are the examples the government gives.
Where Does Keyless Theft End and Another Problem Begin?
Four situations sit beside the relay attack on a keyless car, and each one leads to a different page and a different job.
How Does Keyless Theft Differ From a Stolen Car Key?
Keyless theft takes the car and leaves the key, while a stolen key leaves the car on the drive with a working key in the hands of someone else. The first is answered by prevention, the second by work on the car.
After a key is stolen, a new key is cut and programmed at the vehicle, and missing electronic keys are removed from the immobiliser memory where the vehicle supports it. A mechanical blade still turns a physical lock unless that lock is changed or rekeyed. That work belongs to the lost car keys service, and identity and authority to request the work are checked before it begins.
Which System Does Keyless Theft Exploit?
Keyless theft uses the keyless system exactly as it was built, which is why the theft leaves no damage. The parts of that system, the way the key and the car find each other and the faults the system develops are explained under keyless entry systems.
Where Does the Factory Immobiliser Reach Its Limit?
Every keyless car already carries a factory immobiliser, and it stops a car being started without a recognised key. It does not stop a relay attack, because the relayed signal belongs to a recognised key. The system itself is set out under what a car immobiliser is.
Is a Car Without Keyless Entry at Risk?
The relay attack is a method against passive keyless entry and start, where the car unlocks and starts with the key in a pocket. A car that unlocks on a button press and starts with a blade in the ignition sits outside that method, although a jammed lock command and the diagnostic port apply to it as well. The signs that tell a keyless key from a remote key are listed with the types of car keys.
Keyless theft prevention works in layers, and Matt answers the phone 24 hours a day for the immobiliser layer and for a stolen key.
Frequently Asked Questions
How close does a thief have to be to a keyless key?
A thief only has to be within a few metres of a keyless key to capture its signal, even when the key is inside the home.
That distance is the reason police guidance keeps the key and the spare key away from the car, the doors and the windows.
Where is the safest place to keep a keyless key at night?
The safest place for a keyless key at night is inside a working signal blocking pouch, out of view, away from the front door, the windows and the car.
The spare key goes in a pouch as well, because a spare in a drawer sends the same signal as the key in daily use.
Does switching off the key fob stop a relay attack?
Yes, a keyless fob with its wireless signal switched off gives a relay device no signal to carry.
The function exists on some fobs and not on others. The handbook of the car states whether the fob has it and which buttons switch the signal off and on.
Does a steering wheel lock stop keyless car theft?
No, a steering wheel lock does not stop a keyless car being unlocked or started, but it adds a physical barrier that a radio device does not open.
It is one layer among several. Police guidance lists steering wheel locks, pedal boxes and gear stick locks among security rated products.
Does a Ghost 2 immobiliser stop a relay attack?
A Ghost 2 immobiliser does not stop the doors being opened by a relay attack, and it keeps the vehicle from being driven until the disarm sequence is entered.
Autowatch publishes Ghost 2 as protection against key cloning and relay theft. No security device stops every method of theft, and Inta-Lock does not present Ghost 2 as one that does.
Is it illegal to own a keyless theft device?
The Crime and Policing Act 2026 sets out an offence of possessing an electronic device for use in vehicle theft, and that offence applies only from the date on which the provision is brought into force.
The official legislation website showed the provision as prospective, which means not yet in force, when this article was updated in October 2026. The maximum penalty in the Act is five years imprisonment, an unlimited fine, or both. Importing, making, adapting, supplying and offering to supply such a device are covered by the same provisions.
What do you do when a keyless car has been stolen?
Tell the police and the insurance company straight away when a keyless car has been stolen.
Government guidance is to dial 101 and ask for the local police, with the registration number, the make and model and the colour to hand. The police give a crime reference number, which the insurance company asks for.
How much does keyless theft protection cost?
The cost of keyless theft protection depends on the layers chosen, and for a second immobiliser a quote is agreed before work begins.
A pouch and a steering wheel lock are bought once. A fitted immobiliser moves with the make, the model and the year of the car, because compatibility and the work of the fitting differ between vehicles. No price list is published.