Keyless car theft and a Faraday pouch
Updated: 21 October 2026
The car is on the drive, the fob is on the hall table, and you have read that someone can unlock it without breaking a window. A keyless car theft Faraday pouch stops that particular trick only while the fob that answers the car is inside a shield that still works. Peter F. drew this account from Thatcham Research, Ofcom and UK police pages, plus the listings in the [Faraday pouch comparison](/hub/safes-and-secure-storage/faraday-pouch). He did not stage an attack. A qualifying amazon.co.uk purchase can earn a commission at no extra cost to you. If a theft is happening now, call 999.
The car is on the drive, the fob is on the hall table, and you have read that someone can unlock it without breaking a window.
The car is on the drive, the fob is on the hall table, and you have read that someone can unlock it without breaking a window. A keyless car theft Faraday pouch stops that particular trick only while the fob that answers the car is inside a shield that still works. Peter F. drew this account from Thatcham Research, Ofcom and UK police pages, plus the listings in the Faraday pouch comparison. He did not stage an attack. A qualifying amazon.co.uk purchase can earn a commission at no extra cost to you. If a theft is happening now, call 999.
Our top picks
| Badge | Product | Form | Spare | Stated size | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  Samfolk Samfolk Faraday box and pouch | Hallway box | Box and two pouches | 16 × 12 × 10 cm | 8.5 | about £18.99 | View offer |
 lanpard lanpard medium Faraday pouch | Key-fob pair | Second pouch | 9 × 14 cm | 7.9 | about £3.99 | View offer | |
| Best value |  caslord caslord 2 pack Faraday pouch | Key-fob pair | Second pouch | n/a | 7.2 | about £3.59 | View offer |
On this page
How relay theft works
On a passive keyless car the fob answers a short-range challenge from the vehicle. You walk up, the car sees the fob, and the door opens without a button press on the key. Thatcham Research describes the relay as two people. One stands at the car. The other stands by the house, close enough to the fob to pick up that challenge, and they stretch it over about two metres so the fob replies as if it were beside the door. The car then unlocks and can be started. The fob never leaves your hall. A key you must press to unlock is a different design. The equipment extends a conversation the car and the fob were built to have, and it needs the fob awake and in range of the person by the house.
When a pouch helps
A working pouch helps when the fob that can answer that challenge is fully inside a closed lining, and the spare is too. Overnight that is the hook by the front door, the bowl on the hall table, or a coat near the glass. Seal the fob and close the flap or the lid. Thatcham and the Metropolitan Police both tell you to prove that on your own car. Warwickshire Police say pouches start from about £5 and that you should test a tin the same way. In this set, two-packs from about £3.59 suit one fob and a spare, and the Samfolk box at about £18.99 suits several keys in one place. UK reviews on cheap pouches say the block can fade while the bag still looks new, so retest every few months. The steps are on the how to test a Faraday pouch page.
When a pouch does not help
A pouch does nothing for a fob that is not inside it. The spare on a shelf by the door is enough for the person standing outside. An open flap, a key ring caught in the Velcro, or a lid left off a box leaves the same path. A letterbox key, a broken window, a tow, or a theft while the fob is in your pocket is outside what shielding is for. Tracker has warned that cheap pouches may not work and that a pouch is not the whole of security. Tracker’s figure for vehicles it recovered in 2023 describes Tracker’s own recoveries, not a national theft rate. None of the twelve listings here is Secured by Design on the evidence in the files. A pass on your drive today is a pass for that fob today.
Pouches and illegal kit
A Faraday pouch is passive. Conductive fabric around the fob weakens the radio the fob is trying to send. It does not broadcast. A jammer transmits in order to interfere. Ofcom says using apparatus to interfere with wireless telegraphy is illegal under section 68 of the Wireless Telegraphy Act 2006 unless you are authorised, and Ofcom does not license jammers. A listing that puts signal jammer in the title is using the wrong word for a lined bag. Ofcom also says no pouch is perfect, and that a microwave will cook the keys if someone turns it on. Do not store fobs in the microwave. If you want a metal box, use a tin or a hallway box you can test with the lid shut. That comparison is on the pouch versus box page.
Layers beyond a bag
Police and Thatcham treat the pouch as one layer beside habits you already have. Lock the car, and keep the spare inside a closed pouch or box. A steering lock still matters when the fob is in your pocket. A tracker helps after a theft. It does not stop the relay. Ask the dealer whether your fob sleeps when it is still, or whether a used car still has a spare key coded to it that you do not hold. If you cannot see a motion sensor or a sleep mode in the handbook, assume the fob will answer and pouch it. The bag is the layer you can check this evening with a walk to the drive.
Common questions
What is a relay attack in plain English?
Two people extend the short conversation your car already has with a passive fob. One stands at the car and one stands by the house, close to the key, and they stretch that challenge by about two metres so the fob replies. The car unlocks and can be started. The key stays indoors. It depends on a fob that answers without a button press, and on that fob being in range of the person outside.
Does passive keyless mean push-button start?
Push-button start is common on these cars, and the relay matters because the car will start once it thinks the fob is nearby. The distinguishing point is whether the fob answers without you pressing a button on the key. A key you must click to unlock is not the passive case Thatcham describes. If you are unsure, stand by the locked car with the fob in the house and see whether the door wakes up.
Will a pouch stop all keyless thefts?
No. It reduces the relay path for fobs that are inside a shield you have tested on the car. It does not cover a spare left out, a worn lining, a key taken from a letterbox, or a theft while you are carrying the fob. Thatcham and the police still recommend the test. They do not describe a pouch as theft-proofing.
Are jammers legal?
Ofcom does not license jammers. Causing interference with wireless telegraphy, unless you are authorised, is an offence under section 68 of the Wireless Telegraphy Act 2006. A Faraday pouch is not a jammer. It is a lined bag or box. Ignore listings that use the word jammer as a selling point, and do not buy a transmitter to block the street.
Do motion-sensor fobs remove the need for a pouch?
They can, if the fob really sleeps when it has been still and your handbook or dealer confirms that behaviour on your car. Many owners cannot verify that from the key alone. Until you know the fob stays quiet by the front door, keep it in a tested pouch or box. A motion sensor does not protect the spare if that spare is a different, always-awake fob.
Is a garage enough on its own?
A garage adds a locked door between the street and the car, which matters, and it does not switch the fob off. If the fob is still by the front door, the relay layout Thatcham describes does not require the thief to stand in the garage. Pouch the keys as well. A garage is another layer, in the same way a steering lock is, not a replacement for a sealed fob.
Is microwave storage safe?
No. Ofcom notes that a microwave can shield a fob and that starting the oven will cook the keys. Use a pouch, a tested tin, or a hallway box with the lid shut. Keep the fob out of the kitchen appliance. The car test beside the drive is the check that tells you whether the container you chose is working.
Related pages
Sources
Public UK sources used for this comparison. Listing prices, stars and review counts are the amazon.co.uk figures saved for this set on 19 October 2026.
- Thatcham Research: how to increase your car security (retrieved 19 October 2026)
- Thatcham Research: what is keyless entry and start? (retrieved 19 October 2026)
- Metropolitan Police: preventing car and vehicle theft (retrieved 19 October 2026)
- Ofcom: radio spectrum and the law (retrieved 19 October 2026)
- Ofcom: can a microwave thwart car thieves? (retrieved 19 October 2026)
- This is Money: Tracker warning on cheap Faraday pouches, 22 August 2024 (retrieved 19 October 2026)
- Consumer Rights Act 2015, sections 9 and 11 (retrieved 19 October 2026)
- Warwickshire Police: keyless vehicle theft (retrieved 19 October 2026)