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Relay theft is when someone amplifies the signal from your key fob, sitting inside your house, to trick your car into thinking the key is right next to it. The fix is a Faraday pouch, full stop. You don’t need to understand the electronics to block it. You need a $10 to $20 signal-blocking pouch by the door where you drop your keys, and the whole problem goes away.
Our take
Relay theft sounds high-tech and scary, but the fix is boring and cheap: a Faraday pouch or box that blocks your fob’s signal when you’re not using it. Nothing else on this list matters as much.
What relay theft actually is, in plain terms
Modern keyless entry fobs constantly broadcast a low-power signal so the car can sense when the key is nearby and unlock without you touching a button. That convenience is the weak point. A signal relay device can pick up your fob’s broadcast from inside your house, near a front door or window, and repeat it out to a car parked in the driveway, tricking the car into unlocking as if the key were sitting on the seat. We’re not going to walk through how the devices work or how the attack is carried out step by step. That’s not information this site publishes, and it’s not information you need to protect yourself. What matters is the fix, and the fix is simple enough that you can have it in place tonight.
This isn’t a rare or theoretical problem. Insurance industry data has flagged keyless car theft as a growing share of vehicle theft claims in areas with a lot of passive-entry vehicles, and it tends to cluster on newer models from manufacturers that pushed proximity unlocking as a standard feature. If your car came with a fob you never have to press, walk-up-and-unlock convenience, you’re a candidate for this problem. If your fob still requires a button press before the doors open, you can mostly skip this article.
The one tool that blocks it: Faraday pouches and boxes
A Faraday pouch is a lined bag that blocks radio signals from getting in or out. Drop your fob in one and it can’t broadcast, which means there’s nothing for a relay device to pick up in the first place. Brands like Mission Darkness and Silent Pocket make pouches built specifically for key fobs and phones, and either works fine as long as you actually use it every time you walk in the door. A pouch sitting empty in a drawer doesn’t help anyone.
Mission Darkness Faraday Bag
A signal-blocking pouch sized for key fobs, built by a brand that also sells to security and forensics buyers.
- Blocks cellular, Wi-Fi, Bluetooth, and the fob’s own signal.
- Small enough to keep by the door without it becoming clutter.
- Works for phones too, if you want one pouch for both.
Under $50 No monthly fee
Check price on Amazon
Silent Pocket Faraday Key Fob Pouch
A slimmer, wallet-style option for anyone who wants something less bulky than a full pouch.
- Purpose-built for key fobs rather than a general-use bag.
- Compact enough to clip to a keyring or toss in a bowl by the door.
- Signal-blocking fabric with no batteries or moving parts to fail.
DIY install
Check price on Amazon
How do you know a pouch is actually working?
A quick test: put your fob in the pouch, then walk up to the car and try the door handle the way you normally would with the fob in your pocket. If the door stays locked and the car doesn’t respond, the pouch is doing its job. Some people also test with a phone, since a pouch that blocks a phone’s signal (you’ll notice a dropped call or lost Wi-Fi the moment it goes in) is reliably blocking the weaker fob signal too. Worn or damaged pouches can lose their shielding over time, especially cheaper ones with thin lining, so a periodic re-test isn’t a bad habit if you’ve had the same pouch for a couple of years.
Does turning off keyless entry work?
Some cars let you disable the fob’s passive proximity broadcast through a menu setting, which closes the gap without buying anything. It’s a legitimate option if your model supports it, but it also means digging through a manual or a dealer visit to find the setting, and you lose the walk-up-and-unlock convenience you probably bought the car for in the first place. For most people, a pouch by the door is the lower-friction fix, and you don’t lose any functionality. You just add one habit.
A steering wheel lock is worth pairing with either approach, since it’s a visible deterrent that doesn’t depend on the fob at all. We rank it alongside other physical devices in our guide to car anti-theft devices that are actually worth buying.
Other habits that help
Park in a garage or under a light where you can, since relay theft still requires proximity to the car, and a thief working in the open under a streetlight is taking a bigger risk than one in a dark driveway. Keep the fob away from windows and exterior walls overnight, not just in a pouch but physically further from where a relay device would be aimed. A metal container, like a microwave or a metal tin with a tight lid, can work in a pinch as an improvised Faraday cage if you don’t have a pouch handy, though a purpose-built pouch is more reliable and doesn’t require remembering which drawer the tin is in. Neither of these habits replaces the pouch, they just shrink the odds further on nights when the routine slips.
| Fix | Blocks the signal? | Cost | Effort |
|---|---|---|---|
| Faraday pouch or box | Yes, completely | $10 to $30 | One new daily habit |
| Disable passive keyless entry (if supported) | Yes, at the source | Free | Menu setting or dealer visit |
| Park in garage / under light | No, reduces opportunity | Free | None, situational |
| Steering wheel lock | No, separate deterrent | $25 to $70 | DIY, visible |
Relay theft only threatens cars with passive keyless entry. If your car still uses a traditional key or a fob you have to press, none of this applies to you. For the theft risks that hit every car regardless of key type, see what actually stops catalytic converter theft.
Where this fits with the rest of your car security
A Faraday pouch is a prevention tool, and prevention only gets you so far on its own. If a theft happens anyway, recovery and evidence come from a different layer entirely. See GPS trackers vs dash cams for what each one actually catches after the fact. And if personal safety while you’re out and about matters as much as the car does, our guide to legal self-defense items covers what’s worth carrying alongside it.
None of these layers require much money or effort individually. The pouch is ten dollars, the habit costs nothing, and together they close off the specific weak point that passive keyless entry created. Most owners who’ve had a car targeted once never skip the pouch again, which tells you most of what you need to know about how well it works.
What is relay theft on a car key fob?
It’s when a device picks up your fob’s proximity signal from inside your home and relays it to a car outside, tricking the car into unlocking as if the key were nearby. A Faraday pouch blocks this by stopping the fob from broadcasting at all.
Do Faraday pouches actually work for key fobs?
Yes, a properly lined pouch blocks all radio signals in and out, including the fob’s passive broadcast. The only failure mode is forgetting to use it consistently, or an old pouch with worn-out lining.
Can I just take the battery out of my fob instead?
You can, but it’s more hassle than a pouch since you’d need to reinsert the battery every time you want to use the fob. A pouch achieves the same blocking effect with zero disassembly.
Does aluminum foil work instead of a Faraday pouch?
It can block signal in a pinch if wrapped tightly with no gaps, but it’s unreliable and tears easily with daily use. A purpose-built pouch costs about the same as a takeout order and works consistently.
Which cars are most at risk of relay theft?
Any vehicle with passive keyless entry, where the doors unlock just by having the fob nearby, is a candidate. Newer models that market walk-up unlocking as a headline feature tend to show up most often in theft data.
Who checked this
True Security Gear splits the work in two. One side of the crew verifies specs, certifications, and seller claims against the paperwork; the other installs the gear in real rentals and family homes and lives with it. Nothing gets a recommendation we would not bolt to our own front door. The criteria are on How we evaluate.
