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What is a Faraday pouch?

  • Want to invest in some car security? Start with a Faraday pouch
  • A Faraday pouch will help protect against rising keyless entry car theft
  • We explain what they are, how they work and why you need one

Written by Seth Walton Published: 26 May 2023 Updated: 30 May 2023

Keyless entry systems are hugely convenient pieces of modern car technology as they allow motorists to lock and unlock their cars without the need to press a button. However, keyless entry systems can also leave cars vulnerable to keyless entry theft. Faraday pouches are simple security measure than can minimise this risk for a very small price, but what actually is a Faraday pouch?

Faraday pouches are small key fob container bags designed to block a key’s electromagnetic signal from projecting outward, thus reducing the chance of it being hijacked by a couple of technologically adroit crooks.  

They may harness near 200-year-old technology – Faraday pouches are named after Michael Faraday who invented the first electromagnetic field-blocking cage in 1836 – but they’re still among the most effective car security measures. Be sure to check out the Parkers guide to key trackers for even better protection.

How do Faraday pouches work?

Faraday pouches work by containing the radio signals emitted by keyless entry fobs in a signal-blocking metallic lining, usually a weave of many layers for greater efficacy. So long as the signals can’t leave the pouch, the receiver won’t be able to pick them up and your car should be safer from keyless theft.  

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Car key with electric handbrake
Keyless entry fob

Why do I need a Faraday Pouch?

Relay theft thieves usually work in pairs. One thief will hold a relay amplifier to replicate the signal emitted from a car’s keyless entry key while the second thief will stand by the car holding a signal transmitter.

Once a replicated signal has been established with the car’s keyless entry system in range of the transmitter, the doors will unlock. All without touching the key stored in the house.

Given how easy the task can be and how quietly it can be carried out, keyless entry thefts, or relay thefts as they’re sometimes known, have been on the rise across the country in recent years.

We take all sorts of precautions to ensure our homes and their contents are securely locked away at night. While manufacturers are endeavouring to make keyless entry systems theft-proof, there are still hundreds of models on the road today at risk of keyless theft.

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The KiaSafe case
The KiaSafe case works like a Faraday pouch to protect against keyless theft.

With your key stored away in a Faraday pouch overnight, however, you can rest assured knowing your car won’t be at the same risk.

If you keep your car in a garage at night, be sure to check out our guide on the best garage security products. Looking to protect your garage on a budget? You could opt to reinforce the security on your garage door instead.

Are Faraday pouches 100% effective

Unfortunately, like most security measures, Faraday pouches are not 100% effective. Depending on the quality of your Faraday pouch, some of the signals may still be able to escape. As time goes on and the lining material of the pouch begins to wear, it may become less effective than before.

However, Faraday pouches are still an indubitably worthwhile investment for anyone running a keyless entry system as they lower the risk of theft considerably, even if it isn’t by 100%.  

Mercedes Keyless entry keys

Are all Faraday pouches alike?

No, not necessarily. While they may all feature similar design characteristics, the efficacy of one pouch compared to the next may depend on the quality of the materials used. Most pouches offer great signal protection, but some may be more lighter or more durable than others. Some faraday pouches even offer the space to store bank cards or mobile phones.

Can I test my Faraday pouch?

Yes. Start by putting the key in the Faraday pouch then approach your car. If your car fails to unlock as it usually would with the key so close, the key’s signals aren’t escaping the lining and the pouch is performing as it should.  

You could also try putting another device into the pouch that offers Bluetooth connectivity. If you’re unable to connect to the device via Bluetooth, the pouch is successfully blocking all signals.

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Volvo V60 Recharge Plug-in Hybrid at home
Volvo V60 Recharge Plug-in Hybrid at home

Are Faraday Pouches expensive?

Faraday pouches start from around £5 which, seeing as though they could prevent your multi-thousand-pound car from being stolen, makes them pretty good value for money. If you have multiple cars that you’d like to protect, you could opt for a signal-blocking box instead, though these models can cost anywhere up to £30.