Wrapping a modern car key fob in aluminum foil is described as a simple, low-cost trick that may help protect against certain types of keyless car theft. According to the source, the foil can act as a barrier that blocks electromagnetic signals emitted by the fob, and this may stop thieves from using relay devices to capture and extend the signal to unlock or start a vehicle. The idea is that if the signal is blocked, the relay device cannot pick it up as easily, which may reduce the chances of successful keyless theft attempts that depend on relaying the fob’s signal from inside a home or pocket.

The same source notes that while aluminum foil may provide some level of protection, a purpose-built Faraday pouch is recommended for better security. These pouches are designed to block electromagnetic signals, and the source advises that owners should test their chosen pouch to confirm it actually blocks their specific key fob’s signal. This might involve checking whether the car still responds to the fob while it is inside the pouch. By using these signal-blocking methods and verifying that they work with their own keys, drivers may be able to add an extra layer of protection against keyless car theft techniques that rely on capturing and extending fob signals.