Introduction
Keyless entry has become standard on a huge range of modern cars, letting you unlock and start the engine simply by having the key fob somewhere on your person, with no need to physically insert or even remove it. It's genuinely convenient, but it has also created a well-documented theft method that has caused real concern among drivers, insurers and policymakers alike: the relay attack. This guide explains exactly how relay theft works, how UK car insurers have responded, the new law specifically targeting theft devices, and the practical steps that genuinely reduce your risk.
This guide complements our Comprehensive Car Insurance UK and Car Insurance Claims Guide UK guides, and sits alongside our Black Box Insurance Guide UK guide, which covers telematics devices used primarily for driving-behaviour pricing rather than theft prevention specifically.
Key Terms Explained
- Relay Attack
- A theft method using two linked electronic devices to capture a keyless entry fob's signal and relay it to the vehicle, tricking it into unlocking and starting as though the genuine key were present.
- Keyless Entry
- A vehicle access system allowing the doors to unlock and the engine to start without physically inserting a key, provided the paired fob is within range.
- Thatcham Research
- An independent UK vehicle security research organisation whose approval categories are widely used by insurers to assess and require specific security and tracking devices.
- Thatcham Category S5
- A Thatcham-approved tracking device category combining a subscription-based tracking service with additional verification features, commonly required by insurers for higher-value or higher-risk vehicles.
- Signal-Blocking (Faraday) Pouch
- A pouch lined with material designed to block a key fob's wireless signal from being transmitted or captured while the fob is stored inside it.
Why This Matters
Many drivers assume that because they've never lost or handed over their keys, their car simply can't be stolen without their knowledge, an assumption relay theft directly undermines. Understanding the genuine mechanics of this risk, rather than a vague sense that "keyless cars get stolen," helps you take proportionate, effective precautions and understand exactly what your insurance policy expects of you in return for cover.
This guide also matters because getting the insurance side wrong, misunderstanding a tracker requirement, or failing to disclose relevant security information accurately, can leave you with a declined or reduced claim at exactly the moment you need your cover most.
How a Relay Attack Actually Works
A relay attack typically uses two people working together, each holding a small electronic device. One device is held close to the outside of your home, near where your key fob is likely to be sitting, such as by the front door or hallway, and it captures the fob's low-power wireless signal. This signal is then relayed, essentially retransmitted in real time, to a second device held next to the car, which the vehicle interprets as the genuine key being present nearby. This allows the car to be unlocked and, in many cases, started and driven away, all without the key fob physically moving from inside the house.
Why This Differs From Traditional Car Theft
Unlike traditional theft methods involving forced entry, hot-wiring or a genuinely stolen physical key, relay attacks exploit the wireless convenience feature itself, leaving no obvious sign of forced entry and often no direct evidence at the scene beyond the vehicle simply being gone. This is precisely why the crime has proven so difficult to prevent through physical security measures alone, and why insurers and manufacturers have both had to adapt their approach specifically to address it.
Which Cars Are Most Exposed
Relay attack risk is generally higher for vehicles fitted with keyless entry and keyless start as standard, which increasingly includes a wide range of mainstream models, not only premium or luxury vehicles as was more true in the technology's earlier years. Higher-value vehicles remain a particular target for organised theft specifically because of their resale or export value, but keyless entry itself, rather than price alone, is the underlying vulnerability being exploited.
Manufacturer Security Improvements
Vehicle manufacturers have introduced various countermeasures over time, including motion-sensing fobs that go to sleep when stationary, reducing the window during which a signal can be captured, and updated encryption methods. These improvements genuinely help, but the pace of manufacturer response and criminal adaptation means relay theft risk hasn't been eliminated across the keyless vehicle market as a whole.
Relay Theft vs Other Theft Methods
| Method | How It Works | Typical Evidence Left |
|---|---|---|
| Relay attack | Captures and relays a genuine key fob's signal without the key leaving the house | Often minimal visible evidence of forced entry |
| Key cloning or emulation | Copies or recreates a key's electronic signal or code using specialist equipment | Varies; may involve OBD port access marks |
| Traditional forced entry or hot-wiring | Physical break-in and bypassing the ignition system directly | Visible damage to locks, windows or the steering column |
| Key theft (burglary or robbery) | The genuine key itself is stolen, often during a separate burglary | Evidence of the associated burglary or robbery, rather than the vehicle theft itself |
Understanding which method applies to your situation matters for a claim, since insurers may ask different follow-up questions depending on whether a theft appears to be a relay attack, a cloned key, forced entry, or connected to a separate burglary where keys were taken from inside the home.
The New Law on Theft Devices
Reflecting the scale of the problem, the UK government introduced specific new criminal offences targeting the tools used in relay and similar electronic vehicle theft, contained within the Crime and Policing Act. These offences cover possessing, making, importing, adapting or supplying an electronic device designed or adapted for use in stealing a vehicle, including relay attack equipment, signal jammers and certain key emulation devices, with a maximum sentence of five years' imprisonment.
A Reversed Burden of Proof
A particularly significant feature of the new law is that it shifts the practical burden onto anyone found in possession of this type of device: rather than police needing to prove the device was used in a specific theft, someone found with relay attack equipment who cannot demonstrate a legitimate reason for possessing it can be prosecuted under the new offence itself. This represents a meaningful legal tool aimed specifically at disrupting the supply and possession of theft equipment, rather than only prosecuting after a theft has already occurred.
What This Doesn't Change
It's worth understanding that this legislation targets the supply and possession of theft devices; it doesn't retrospectively make your specific vehicle more secure. Existing keyless vehicles remain just as technically vulnerable to relay attack as before the law changed, meaning the practical prevention and insurance considerations covered throughout this guide remain just as relevant.
How Insurers Have Responded
UK motor insurers have responded to the scale of keyless theft claims in several ways: adjusting how they price cover for higher-risk keyless models, asking more detailed security-related questions at application, and, for a growing number of higher-value or higher-risk vehicles, making a specific tracking device a condition of cover rather than simply an optional discount.
Underwriting Reflects Real Claims Data
Because insurers price risk based partly on their own claims experience, models and areas with a demonstrated higher incidence of keyless theft claims are more likely to see tracker requirements, higher premiums, or both, reflecting the insurer's own genuine loss experience with that specific risk category rather than an arbitrary policy.
Thatcham Tracker Categories Explained
Thatcham Research operates a widely recognised set of approval categories for vehicle security and tracking devices, and insurers commonly reference these categories directly in policy wording when specifying a required device rather than describing requirements in vague terms.
| Category | General Function | Typical Insurer Use |
|---|---|---|
| Alarm and immobiliser categories | Detect unauthorised entry and prevent the engine being started without the correct key | Often standard or expected on most modern vehicles |
| Tracking device categories (including S5) | Locate a vehicle after theft, sometimes combined with driver verification and automatic alerts | Increasingly required as a specific policy condition for higher-value or higher-risk keyless models |
Where a policy specifies a particular Thatcham category, fitting an equivalent but differently categorised device may not satisfy the condition, so checking the exact requirement with your insurer before purchasing or relying on an existing device is essential rather than assuming any tracker will do.
Policy Conditions and What Happens If You Don't Comply
When a specific security device is written into your policy as a condition, rather than simply offered as an optional discount, this becomes a genuine term of your cover, not just a recommendation. Failing to fit the required device, allowing a subscription-based tracking service to lapse, or removing a device without informing your insurer can all potentially affect a future theft claim.
Declaring Security Devices Accurately
Just as importantly, accurately declaring what security devices are actually fitted, and keeping this information updated if you change vehicles or upgrade your security setup, is essential. Overstating your vehicle's security to secure a lower premium carries the same non-disclosure risk as inaccurate information on any other part of an insurance application.
How Insurers Investigate a Theft Claim
Following a reported theft, insurers typically investigate the circumstances before settling a claim, which can include reviewing any available tracker or telematics data, checking whether required security conditions were met, requesting a police crime reference number, and in some cases requesting further information about where and how the vehicle was normally kept and secured.
Why This Process Can Take Time
Relay theft claims can take longer to settle than more straightforward claims, partly because the absence of obvious forced entry can prompt a more thorough investigation to confirm the circumstances genuinely match a covered theft event rather than, for example, a dispute over ownership or an inconsistency in the account given. This is a normal part of the process rather than necessarily a sign the claim will be refused.
Practical Prevention Measures
No single measure eliminates relay theft risk entirely, but combining several genuinely reduces your exposure considerably. Practical steps include storing your key fob away from external walls and doors, using a genuine signal-blocking pouch, fitting a visible steering wheel lock or similar physical deterrent, considering an OBD port lock to prevent key reprogramming via the vehicle's diagnostic port, and parking in a garage or well-lit, overlooked area where practical.
Ask Your Manufacturer or Dealer About Motion-Sensing Fobs
If you're unsure whether your specific key fob includes motion-sensing technology that reduces signal transmission when stationary, your vehicle manufacturer or dealer can confirm this, and in some cases a fob upgrade or software update may be available to add this protection to an existing vehicle.
Do Signal-Blocking Pouches Actually Work?
Genuine, properly constructed signal-blocking pouches can meaningfully reduce relay attack risk by physically preventing your key fob's signal from being transmitted while stored inside, effectively removing the signal a relay device would otherwise capture. However, effectiveness varies considerably between products, and a pouch that has been damaged, is poorly made, or is used inconsistently offers little genuine protection.
Treat It as One Layer, Not a Complete Solution
Relying on a signal-blocking pouch alone, without also considering other measures such as a tracker where required by your policy, or being mindful of where keys are stored within the home, doesn't provide complete protection. The strongest practical approach combines several layers of prevention rather than relying on any single measure.
Parking and Storage Considerations
Where and how you normally keep your vehicle overnight is a standard question on most car insurance applications, and it's genuinely relevant to relay theft risk too, since a vehicle parked on a driveway close to the home, in a locked garage, or on an open street each present a different practical risk profile. Insurers may ask specifically about overnight parking arrangements, and answering accurately, including if this changes after your policy starts, is important for the same reasons accuracy matters across any other part of your application.
If Your Parking Situation Changes
Moving from off-street to on-street parking, or vice versa, partway through a policy is worth reporting to your insurer, since this genuinely affects the risk profile they originally priced your policy against, and failing to update this information could affect a future claim.
Doorbell Cameras and CCTV Evidence
Video doorbells and home CCTV systems have become increasingly common, and footage from these devices can be genuinely valuable both to police investigating a relay theft and to your insurer assessing a claim, sometimes capturing the moment thieves approach the property to attempt signal capture, even if the vehicle itself is out of shot. If you have any relevant footage, providing it promptly to both the police and your insurer can support both the criminal investigation and your own claim.
Checking Footage Retention Periods
Many doorbell and CCTV systems only retain footage for a limited period before it's automatically overwritten, so reviewing and saving any potentially relevant footage as soon as possible after discovering a theft, rather than waiting, helps ensure important evidence isn't lost.
The Effect on Premiums
Keyless theft risk is one of several factors insurers weigh when pricing cover for a specific make and model, alongside broader factors such as vehicle value, repair costs and general theft statistics for that model. Fitting a required or recommended tracking device can sometimes support a more favourable premium, reflecting the reduced theft and non-recovery risk from the insurer's perspective, though this varies between insurers and isn't guaranteed for every policy.
Impact on Your No Claims Discount
A successful theft claim, including one arising from a relay attack, is generally treated in a similar way to other claims where there's no other party to pursue costs from, meaning it can affect your no claims discount depending on your specific insurer's approach. Reviewing how your particular policy treats a theft claim for no claims discount purposes, before you need to rely on it, helps set realistic expectations. Our No Claims Bonus Explained UK guide covers this area in more detail.
Company Cars and Fleet Considerations
Businesses running fleets of keyless vehicles face the same underlying relay theft risk multiplied across multiple vehicles, often parked overnight at varied locations including employees' homes, making consistent security practice harder to enforce than for a single privately owned car. Fleet policies may include their own specific tracker and security requirements, and businesses should ensure drivers understand and follow these consistently, since a single non-compliant vehicle can affect the outcome of a claim for that specific car. Our Fleet Insurance UK guide covers wider fleet insurance considerations in more detail.
Outstanding Finance and GAP Insurance
If your car is stolen and not recovered, your motor insurer will typically pay out based on the vehicle's market value immediately before the theft, following the same principles as a total loss or write-off settlement. If you still owe more on car finance than this market value, perhaps due to how quickly some vehicles depreciate, you can be left with a genuine shortfall to cover personally unless you have a separate GAP insurance policy specifically addressing this difference. Our GAP Insurance UK guide explains how this cover works in full detail.
Making a Claim
If your car is stolen, report it to the police as soon as possible and obtain a crime reference number, then notify your insurer promptly, providing full details of the circumstances, your vehicle's security setup, and any tracker or dashcam data that might be relevant. Our Car Insurance Claims Guide UK guide covers the wider claims process, including timescales and documentation, in more detail.
If a Claim Is Declined or Disputed
If a theft claim is declined or reduced, the insurer must explain their reasoning in writing, and you're entitled to challenge this decision through the insurer's own complaints process, escalating to the Financial Ombudsman Service if the dispute remains unresolved. Understanding the specific policy condition or exclusion the insurer is relying on is the essential first step in assessing whether a challenge is genuinely worthwhile. Our Financial Ombudsman Service and Insurance Complaints UK guide explains this process in full.
Real-World Examples
Example: A Claim Settled Without Complication
A driver's keyless car is stolen overnight despite the key being kept away from external doors. With a Thatcham S5 tracker fitted as required by their policy, the vehicle is recovered by police within hours, and the insurer processes a straightforward claim for the resulting damage.
Example: A Condition Not Met Complicates a Claim
A driver's policy specifies a Thatcham-approved tracker as a condition of cover for their higher-value keyless vehicle, but the subscription had lapsed several months earlier without the driver realising. Following a theft, the insurer's investigation identifies this gap, and the claim outcome is affected as a result, illustrating the importance of maintaining required devices continuously.
Example: A Finance Shortfall After a Total Loss
A driver's financed vehicle is stolen and not recovered. The insurer's payout, based on the car's market value, is meaningfully lower than the outstanding finance balance. Because the driver had arranged GAP insurance when purchasing the car, the shortfall is covered separately, avoiding a significant unexpected personal cost.
Common Mistakes to Avoid
- Assuming standard comprehensive cover has no specific security conditions attached for a keyless vehicle.
- Letting a required tracker subscription lapse without realising it affects your cover.
- Relying on a signal-blocking pouch alone without considering other layers of protection.
- Overstating your vehicle's security setup when applying for or renewing cover.
- Not checking how a theft claim would affect your no claims discount before you need to rely on it.
- Assuming your insurance payout will automatically cover any outstanding car finance in full.
Common Myths
- Myth: Relay theft only affects expensive luxury cars. Keyless entry itself, now common across a wide range of mainstream models, is the underlying vulnerability, not price alone.
- Myth: A signal-blocking pouch makes your car completely theft-proof. It meaningfully reduces risk but isn't a guaranteed, standalone solution.
- Myth: The new law makes existing keyless cars more secure. It criminalises possessing theft devices but doesn't change your specific vehicle's underlying technical vulnerability.
- Myth: Any vehicle tracker satisfies a Thatcham-specified policy condition. Insurers often specify an exact category, and a differently categorised device may not meet the requirement.
- Myth: Insurance will always cover the full amount owed on car finance after a theft. The payout reflects market value, which can be less than the outstanding finance balance without separate GAP cover.
Frequently Asked Questions
What is a relay attack and how does keyless car theft work?
A relay attack uses two linked electronic devices to capture the signal from a keyless entry fob, often while it sits inside your home, and relay it to the car outside, tricking the vehicle into thinking the genuine key is nearby so it can be unlocked and started without the key ever leaving the house.
Is it now illegal to own a relay attack device in the UK?
Yes. Under the Crime and Policing Act, possessing, making, importing or supplying an electronic device designed or adapted for use in vehicle theft, including relay attack equipment and signal jammers, is a specific criminal offence carrying a maximum sentence of five years' imprisonment.
Do I need a Thatcham-approved tracker to insure a keyless car?
Not always, but increasingly for higher-value or higher-risk keyless models, some insurers make fitting a Thatcham-approved tracking device, commonly a Thatcham Category S5 system, a specific condition of cover, and failing to maintain a required device can affect a future claim.
Will my insurance claim be refused if my keyless car is stolen?
Not automatically, but a claim can be refused or reduced if a required security device wasn't fitted or maintained as a specific policy condition, or if the insurer's investigation finds the vehicle wasn't kept or secured in line with the policy's stated requirements.
Does a Faraday pouch actually stop relay theft?
A genuine, correctly tested signal-blocking pouch can meaningfully reduce relay attack risk by preventing your key fob's signal being captured, though effectiveness varies between products, and it should be treated as one layer of protection rather than a complete guarantee.
Does a keyless car theft claim affect my no claims discount?
A successful theft claim is generally treated as a fault claim for no claims discount purposes, since there's no other party to recover costs from, though this can vary between insurers, so checking your specific policy terms is worthwhile.
What happens if my car is stolen and I still owe finance on it?
Your motor insurer pays out based on the car's market value at the time of theft, which can be less than your outstanding finance balance, potentially leaving a shortfall unless you have GAP insurance specifically covering this difference.
References and Editorial Standards
This guide is reviewed regularly by the ShopTera Editorial Team and reflects general, well-established principles of how relay attack theft works, how UK insurers approach keyless vehicle security requirements, and the new criminal offences introduced under the Crime and Policing Act targeting vehicle theft devices. Specific insurer policy conditions, Thatcham category requirements and legal detail can change over time, so always confirm current requirements directly with your insurer and check official government guidance for the latest legal position. This guide is intended for general educational purposes and does not constitute legal advice.
| Version | Date | Change |
|---|---|---|
| 1.0 | 21 August 2026 | Initial publication |
Conclusion
Relay attack theft is a genuine, well-documented risk for keyless vehicles, but understanding exactly how it works, what your insurer specifically requires in terms of security devices, and which prevention measures genuinely reduce your exposure puts you in a considerably stronger position. Combining practical prevention, meeting any required policy conditions in full, and understanding how a theft claim would actually be handled, including any finance shortfall risk, means you're properly prepared rather than relying on comprehensive cover alone to solve every part of this problem.