How to stop relay car theft
The most reliable way to stop relay car theft is to block your key fob's signal when the car is parked, because a relay attack only works if there is a live signal to relay. A simple Faraday pouch or signal-blocking box that you drop the key into at home cuts the fob off from the receiver a thief would hold against your window, and the attack falls apart before it starts.
That single habit defeats most relay attempts, but a determined crew has other tricks, so the right approach in South Africa is to layer a few cheap, practical defences and back them with a monitored tracker that recovers the car if everything else is beaten.
Compare South Africa’s leading trackers & dashcams in one short form.
Get my quotesBlock the fob signal at home
The cheapest and most effective step is a Faraday pouch or metal signal-blocking tin for your keys, kept by the door where you naturally drop them. With the fob inside, its signal cannot reach a relay receiver held outside the wall, so there is nothing to relay and the car will not respond.
Make it a household rule that every keyless fob - including the spare - lives in the pouch when you are home. A spare key left signalling in a kitchen drawer is just as exploitable as the one in your pocket, and crews know to try around the whole house.
Check whether your fob can sleep
Some newer keys have a motion sensor that puts the fob to sleep when it has been still for a while, which means it stops broadcasting overnight and cannot be relayed. Check your owner's manual or ask the dealer whether your fob supports this, and how to enable it.
If your fob has the feature it is worth turning on, but treat it as a bonus rather than your main defence - not every fob has it, the timing varies, and a key that is picked up and moved wakes straight back up. The pouch is the dependable layer.
Add a physical barrier the relay cannot beat
A relay attack gets the car started, so a barrier that physically prevents driving still helps. A visible steering lock is a strong deterrent because it adds time and noise, and time and noise are exactly what a silent-minute relay crew wants to avoid.
Better still is a hidden aftermarket immobiliser that will not let the engine run without a separate secret action, because it defeats the relayed start entirely. Where the fob signal does get through, the immobiliser is the layer that stops the car moving.
Park to make the attack harder
Where you leave the car matters. Parking inside a locked garage puts walls and distance between the fob and any relay device, and parking with the car boxed in by another vehicle simply makes a quick getaway harder. Both raise the effort and the risk for a thief.
Outside the home, prefer busy, well-lit, monitored parking over a quiet street. Relay theft thrives on privacy and a clear exit; remove those and many crews will not bother.
Fit a monitored tracker as your safety net
Assume that none of the above is perfect and plan for the case where the car is driven off anyway. A monitored, recovery-grade tracker does not depend on the key, so a relayed start followed by an unauthorised 2am drive is exactly the pattern a good control room treats as an alarm and acts on.
This is the layer that changes the outcome rather than just the odds. Signal-blocking lowers the chance of the attack working; the tracker is what actually gets the car back when it does.
Why layering beats any single fix
No one of these steps is foolproof. A fob can be left out of its pouch, a sleep timer can be beaten by simply jostling the key, an immobiliser can in theory be worked around with time, and a tracker recovers rather than prevents. Each layer covers the gap the others leave.
Stacked together they make your car the wrong kind of target: a relay crew hunting an easy, silent minute meets a dead signal, then a car that will not start, then a tracker already alerting a control room - and moves on.
A 30-second routine before you walk away
Turn the defences into a habit and they cost you nothing. At home, the fob goes straight into its Faraday pouch by the door, spare included. At the car, you physically pull the handle to confirm it is locked rather than trusting the beep, especially in a car park where lot-jamming is common.
Once a month, sanity-check the rest: confirm the immobiliser arms, glance that the tracker app shows the car reporting, and make sure everyone who drives the vehicle knows the routine. A defence you perform automatically is worth far more than an expensive one you forget to use.
Choosing a Faraday pouch that actually works
Not every signal-blocking pouch is equal, and a cheap one with worn lining can leak enough signal to be relayed. Buy a reputable double-lined pouch or a solid metal tin, and test it on purchase by sealing the key inside and confirming the car no longer unlocks or starts through it.
Re-test occasionally, because the shielding can degrade with daily folding and wear. A pouch you have actually verified is worth far more than one you assume is working.
Do not forget the spare key
Households lose cars to relay theft through the spare key as often as the main one. A spare left signalling in a kitchen drawer, a bowl by the door or a bedside table is just as exploitable, and crews know to try around the whole property, not only the front door.
Treat every fob the same: main key, spare key and any third key all live in a pouch or tin when at home. The defence is only as strong as the least-protected key in the house.
What to do if you suspect an attempt
If you find the car unlocked unexpectedly, or have reason to think your fob was reached, act rather than wait. Pouch all keys immediately, move the car into a garage or a more visible spot, and confirm with your provider that your tracker is reporting and your contact details are current.
Consider mentioning it to neighbours and, if there is camera footage, to the police, since relay crews often work an area. A single noticed attempt is a useful early warning to close every gap before they return.
The bottom line: cheap habits, real protection
What stands out about stopping relay theft is how little it costs to do well. A signal-blocking pouch is inexpensive, checking the door is free, and parking sensibly costs nothing - yet together they defeat the great majority of relay attempts before they start. The only meaningful spend is the monitored tracker, and that earns its place as the recovery layer behind everything else.
The mistake owners make is treating relay theft as a problem they cannot do anything about, and so doing nothing. In reality it is one of the more preventable methods, precisely because it depends on a live fob signal you can simply take away.
Build the habits, pouch every key, fit an immobiliser if the car warrants it, and keep a recovery-grade tracker live. Do that and a relay crew hunting an easy, silent minute meets a dead signal and a car that fights back - and moves on to a softer target.
Related questions
What is the single best defence against relay theft?
A signal-blocking Faraday pouch for the key, used consistently at home. It removes the live fob signal the attack depends on, so most relay attempts simply fail before they begin.
Do Faraday pouches really work?
Yes, a genuine signal-blocking pouch or tin stops the fob's radio signal escaping, which is exactly what a relay receiver needs. Test yours by sealing the key inside and confirming the car no longer responds to it through the pouch.
Will a steering lock stop a relay attack?
It will not stop the car being unlocked or started, but it physically blocks driving and adds visible effort and time, which deters the quick, quiet crews that favour relay theft. It works best alongside signal-blocking and a tracker.
Can an immobiliser stop relay theft?
A hidden aftermarket immobiliser can, because it prevents the engine from running without a separate secret action, defeating the relayed start even if the doors open. It is one of the stronger physical layers.
Why fit a tracker if I am already blocking the signal?
Because no preventive layer is perfect, and a monitored tracker is the only thing that actually recovers the car if a relay attack does succeed. Prevention lowers the odds; the tracker changes the outcome.
Protecting a vehicle in South Africa? Compare the leading tracking providers and dashcams in one place — and get quotes from the right ones in minutes.
Get dashcam & tracking quotes