Keyless Car Theft: Relay Attacks and How to Cut the Risk

How does keyless car theft work?

A car with keyless entry unlocks and starts when it detects its key nearby, with no button pressed. A relay attack tricks that check. Thieves use a pair of devices: one is held close to where the key is kept, often near the front door, and picks up the key's signal; the second, beside the car, passes that signal on. The car behaves as if the key were standing next to it.

The key never leaves the house, and nothing is broken. That is why it often goes unnoticed until the morning. Other methods target the car's own electronics rather than the key, which is why carmakers and the law have both moved against the devices involved.

What does the Crime and Policing Act 2026 change?

It makes it an offence to possess or supply electronic devices used to steal vehicles, such as key emulators and signal relay equipment. The Act received Royal Assent in March 2026, as Thatcham Research reported. There is a defence for a person who had no intent and no suspicion that a device would be used for theft.

The offence is about the equipment itself, so it applies before any car has been taken.

For auto locksmiths, legitimate key programming equipment is part of the job. That is one reason to expect a locksmith to ask for the V5C logbook and ID before making any key.

Do Faraday pouches work?

A Faraday pouch is a bag or box lined with material that blocks radio signals. With the key inside, a relay device cannot pick it up. They work when they are intact and closed properly, and fail when the lining wears or the flap is left open.

Test yours. Put the key in the pouch, close it, walk to the car and try the door handle. If the car unlocks, the pouch is not blocking the signal. Repeat the test every few months, because linings wear with use.

A metal tin can do the same job if it fully encloses the key, and the same test tells you whether it does.

What else reduces the risk?

Several simple steps, best used together:

- Keep keys away from doors and windows, so a device outside cannot reach them. - Check whether keyless entry can be switched off. Some cars allow this in the settings or the handbook explains a button sequence. - Check whether your key sleeps. Some newer fobs stop transmitting when left still; the handbook says if yours does. - Use a visible steering lock or another physical device. It adds a physical step that no signal can get round. - Park in a garage or a well-lit place where you can. - Keep the car's software updated where the maker offers updates.

None of these replaces the others. Each one removes one easy route.

What should you do with spare and lost keys?

Treat every key as part of the risk. Keep the spare in a signal-blocking pouch or tin too, since a spare on a hook by the door is an easy signal for a relay device.

If a key is lost or stolen, an auto locksmith or a dealer can programme a new one and, on many cars, remove the lost key from the car's memory so it no longer starts the engine. Ask for this by name. A replacement key, cut and programmed, costs about £100 to £282, from StageMyCar's locksmith range and WhoCanFixMyCar's 2026 booking average.

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