Start with your vehicle's keyless features
A Faraday pouch is designed to block signals when the key is stored inside the appropriate compartment. Police recommend considering signal-blocking storage for keyless fobs. Check your vehicle's features and owner instructions rather than assuming that every start-button vehicle needs the same accessory.
Check the pouch instructions
Use the intended shielded compartment and close it as the manufacturer directs. A storage pocket may not be the signal-blocking section. Do not assume a particular fabric, appearance or price proves effectiveness. The relevant question is whether the product works with the key and vehicle in ordinary use.
Test it with the actual key
Police guidance recommends testing a pouch by placing the key inside and checking whether the vehicle still responds to normal keyless entry. Keep any other working keys away from the test so they do not confuse the result. Follow the pouch and vehicle instructions; one check is not a guarantee of permanent performance.
Inspect and recheck
Check for damage and retest periodically rather than assuming an unsupported fixed replacement interval. Consider how spare fobs are stored too. Do not overfill a pouch or rely on it when the closure is damaged. If you are unsure about the result, ask the manufacturer for guidance.
Keep the limits clear
Signal-blocking storage does not make a vehicle theft-proof or replace physical security and normal locking checks. Use current advice relevant to your vehicle. A missing-key enquiry should separately address what the replacement work changes about the lost key's access.
Related services and enquiries
Compare lost-key replacement with spare-key duplication, or read about key fob programming. Check published price guidance and send your vehicle details.
Source and further reading
Warwickshire Police: keyless vehicle security. Check the guidance relevant to your own vehicle.