Relay Car Theft Explained: How It Works and How to Protect Yourself

This guide explains how relay theft works, why most keyless cars are vulnerable, and which technologies — such as Ultra-Wideband (UWB) — actually stop the attack.

Relay car theft is one of the most common ways thieves in the UK steal modern cars with “keyless entry/keyless start”. A thief stands near your house with equipment that picks up your key fob’s signal and relays it wirelessly to equipment an accomplice, standing next to your car, is holding. Your car believes the key fob is just outside the car, unlocks, and once the accomplice gets inside with his equipment your car then believes the key fob is inside the car and starts.

Relay car theft uses the same technique for cars that just have “keyless start” except the accomplice has to break into the car first to get his equipment inside the car, the alarm activates but the moment the engine starts, many alarms deactivate automatically – this method is less common than classic silent relay theft of full keyless-entry vehicles (the above). The need for a visible forced entry, alarm activation and prolonged time inside the cabin makes it a much higher-risk approach for criminals, and therefore far less attractive. Click on the links below for more detail.

• Relay theft happens because 86% of keyless entry/start or keyless start car key fobs transmit a signal that can be relayed.
• Check ADAC’s list to see if your car is vulnerable.
• UWB offers the strongest protection, but is still rare.
• Motion-sensor fobs help, but are not universal.
• You may have car settings that can disable keyless entry, but this doesn’t stop relay theft completely.
• Good Faraday pouches block the key signal — but must be tested and replaced regularly.
• UWB and Digital Key 3.0 systems offer the best long-term protection.
• Phone-as-Key (BLE) systems are safer than old keyless fobs, but the physical fobs supplied with the car may still be vulnerable if they lack motion sensors.
• Digital Key (NFC) is immune to relay attacks, but the physical fobs supplied with the car may still be vulnerable if they lack motion sensors.
• Signal Jammers – Why Your Car Might Not Lock
• New UK Law Targets Keyless-Car Theft Tools

It’s also worth noting that vehicle theft is not limited to relay attacks. House break-ins to steal car keys are common, so keys should not be left in obvious or easily accessible places such as hall tables, kitchen counters, or near doors and windows.