What device do thieves use to steal keyless cars?

Relay boxes: the most common tool

A relay box is actually a pair of devices that capture and re-transmit your key fob's signal. One is held near where the key sits in your home, the other at the car, and together they fool the vehicle into thinking the key is present, so it unlocks and the push-start works. It is the signature tool of keyless theft.

Relay theft is silent and fast because it uses the car's own legitimate keyless handshake, just stretched across a distance. It is defeated most simply by blocking the fob's signal with a Faraday pouch.

OBD key programmers

An OBD key programmer plugs into the car's diagnostic port and registers a brand-new blank key to the vehicle. Once a thief has got inside, the tool can create a working key in under two minutes, after which the car treats the thief as a legitimate owner.

This method is blocked by an OBD port lock that denies access to the socket, and neutralised by an OBD immobiliser that demands a PIN before the car will start regardless of the key.

Code grabbers

A code grabber captures the radio signal from a remote and attempts to replay or exploit it. Modern cars use rolling codes that make simple replay harder, but grabbers - sometimes combined with jamming so your lock command fails and is captured - remain part of the toolkit for some vehicles.

Defending against them overlaps with defending against jamming: confirm the car physically locks, and rely on a tracker that does not depend on the same vulnerable signals.

Signal jammers

Jammers are used two ways against keyless cars: to block your remote so the car never locks (lot jamming), and to block the mobile signal a tracker needs so a theft goes unreported. Both are illegal and both are cheap and common.

The answers are behavioural and technical: check the door is locked before walking away, and choose a tracker with jamming detection plus a radio-frequency recovery beacon that a jammer cannot silence.

Why these devices succeed

The common thread is that every one of these tools exploits convenience features - passive entry, push-button start, remote locking, diagnostic access - rather than breaking real security. The more seamless the keyless experience, the more surface there is for a cheap device to abuse.

That is why no single gadget on the owner's side is a complete answer. Each thief tool has a specific counter, and a sensible setup stacks those counters together.

Building a defence against the whole toolkit

Block the relay box with a Faraday pouch, block the OBD programmer with a port lock and a PIN immobiliser, blunt code grabbers and jammers by always confirming the car is locked, and back the lot with a monitored, recovery-grade tracker so that anything which slips through still ends in recovery.

Layered this way, a keyless car stops being the easy, silent target these devices are built to exploit. The thief meets a dead fob, a car that will not start, and a tracker already raising the alarm.

The cheapest effective counter for each tool

Each thief device has a low-cost counter. The relay box is beaten by a Faraday pouch costing very little. The OBD programmer is blocked by an OBD port lock and neutralised by a PIN immobiliser. Code grabbers and jammers are blunted by the free habit of physically confirming the car locked.

Stack those cheap counters and add one paid layer - a monitored tracker - and you have answered the entire toolkit without spending a fortune. The thief's advantage comes from cheap, common devices; your advantage comes from cheap, common defences plus recovery.

Which cars these devices target most

These tools are aimed squarely at cars with passive keyless entry and push-button start, because that is the convenience they exploit. As keyless systems have spread from premium models down into the mid-market, the pool of vulnerable vehicles has grown well beyond luxury badges.

If your car unlocks as you walk up to it without pressing a button, assume it is a candidate for relay and related attacks and protect it accordingly, regardless of its price.

Layering the counters effectively

Each device has a counter, and the trick is to stack them so the gaps line up: a Faraday pouch kills the relay box, an OBD lock and PIN immobiliser kill the programmer, a physical lock check defeats jamming and grabbers, and a tracker recovers anything that gets through.

Layered this way, a thief must beat several independent defences in sequence, which is usually enough to send them looking for an easier car.

What insurers expect on keyless cars

Insurers are well aware of keyless theft, and on higher-risk or financed keyless cars they frequently require an approved, monitored tracker as a condition of cover, often with a premium discount for fitting one. A factory app does not satisfy that requirement.

So beyond the physical counters, the tracker is the layer your policy is most likely to insist on - and the one that turns a stolen keyless car back into a recovered one.

Staying ahead as the tools evolve

The thieves' toolkit does not stand still - relay devices gain range, programmers cover more models, jammers get cheaper - so the right mindset is to defend the categories of attack rather than chase each new gadget. Block the signal, guard the port, confirm the lock, and recover what gets through, and you are covered as the specific devices change.

This is why the layered approach ages well. A Faraday pouch defeats any relay box, present or future; a PIN immobiliser defeats any programmed key; a jam-aware tracker handles any jammer. The counters are general, even as the tools evolve.

Keep the layers current - tracker live, immobiliser armed, keys pouched - and you do not need to track every new device on the market. You have already closed the doors they all rely on.

Turning the toolkit knowledge into action

Knowing the devices is only useful if it changes what you do, so it is worth turning the list into a short plan. For the relay box, the action is a Faraday pouch for every key at home. For the OBD programmer, it is a port lock and a PIN immobiliser. For code grabbers and jammers, it is the free habit of physically confirming the car has locked before you walk away.

Behind all of those sits the recovery-grade tracker, the layer that does not care which device was used because it recovers the car regardless. That is the point worth holding onto: the thief's advantage comes from a handful of cheap, specific tools, and your advantage comes from a handful of cheap, specific counters plus one paid layer that covers the outcome.

Put the plan in place once - keys pouched, port guarded, lock checked, tracker live - and a keyless car stops being the easy, silent target these devices are designed to exploit. A thief running through their kit meets a dead fob, a car that will not start, a lock that held, and a tracker already raising the alarm, and almost always moves on to an easier car instead.