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What is a factory fitted immobiliser and do I have one?

Immobilisers can stop your car from being stolen. Read on to find out how Thatcham-approved immobilisers form an integral part of a modern car security system, often with a car alarm, and why car insurers like them so much.
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What is a factory fitted immobiliser and do I have one?

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Does an immobiliser or alarm affect my insurance?

Insurers know that a good security system greatly reduces the risk of a vehicle being stolen and are therefore keen to know what sort of system you have on your car. 

Many cars will only have an immobiliser while some will have both a factory-fitted immobiliser and alarm from new. Older vehicles may not even have an immobiliser or alarm at all. 

As immobilisers and alarms lower the risk of thieves making off with your car, insurers will adjust their premiums accordingly, charging you less if they think your car’s security system makes it less likely that your car will ever be stolen. 

What is a car immobiliser?

An immobiliser is an electronic security device, hidden within the fabric of your car. Immobilisers are designed to stop the engine from starting if a thief uses a fake key in your ignition or tries to hotwire your car like in the films. 

Over the years, as technology has improved, immobilisers have become increasingly sophisticated, with additional features as opposed to merely rejecting unauthorised access each time someone tries to start your car.

Research suggests that from the late 1990s onwards, when immobilizers became increasingly widespread in the UK and continental Europe, the number of cars being stolen began to fall dramatically as car thieves faced a bigger challenge than ever before. 

How does a car immobiliser work?

Your key contains a transponder chip that stores the vehicle’s unique security code. When you use your key in the ignition or fob to start the car, an electronic code is sent to your car’s electronic control unit. This triggers the mechanism that allows your car engine to start. 

If a thief tries to start the car without the correct key, the immobiliser should prevent the engine from starting as it will not receive the right electronic message.

Along with rejecting unauthorised attempts at starting the car each time the correct code is missing some engine immobilisers will put the car into a timed no-start condition as soon as the unauthorised attempt has been detected. 

Other newer systems, as opposed to having just one secret electronic security code, will generate a second code each time the vehicle is used. Certain immobilisers have also been configured to alert security firms through satellite or smartphone technology of an illicit attempt to start the car.

How can I check if my car immobiliser is working? 

To check your immobiliser is working correctly, you could try using some sort of unauthorised key to start your car. But faulty immobilisers usually show up without having to attempt a break in.

If there is an issue with your immobiliser, you might encounter problems such as suddenly not being able to lock your car remotely with the key fob, or not being able to unlock your car. 

You may also find that you are unable to start your car, even with the correct key, including just not being able to turn your key in the ignition. 

Immobiliser problems are often linked to some sort of damage occurring to the key fob and can often be solved quite easily. You may simply just need to replace the battery in the key fob to solve these issues. A malfunctioning key fob could also cause your car alarm to go off. 

Do immobilisers work?

Car makers are constantly re-evaluating security system technology to ensure they stay one step ahead of thieves. 

While car theft is much less common than it used to be, the hacking of immobilisers has occurred from time to time, being more of a problem on certain factory-fitted security systems than others. 

Some researchers have claimed to be able to decipher the magic code of certain security systems within 30 minutes, enabling them to start the vehicle.  

Over recent years, security systems have become increasingly advanced as technology has developed, making it difficult to see how thieves can have much chance of breaking into the more modern systems. But thieves will always search for a weakness they can exploit, so car owners and manufacturers can never be complacent.

Does my car already have an immobiliser?

You might well be asking the question, does my car have an engine immobiliser at all? If your car was sold as a new car in the UK from October 1, 1998, onwards, then it should have a factory-fitted immobiliser built-in, as from this date they became mandatory in the UK. 

If you have a car that was manufactured before this time, even if it was sold as new in the UK, there is a good chance it will not have a factory-fitted immobiliser at all. 

Should you own a second-hand imported car, it is also worth considering that different countries made factory-fitted immobilisers compulsory on different dates. While immobilisers were standard for new cars in many Europe from 1998, it was some years later in the US and Canada.

Many people like to own a classic car on a multi-car insurance policy. The owners of Triumph Spitfires and vintage Mustangs should take note and ensure they have at least a basic immobiliser fitted, as older classic cars will not have factory-fitted immobilisers. 

How do I know if my car is fitted with an immobiliser? 

When you buy these kinds of cars second hand you may find the previous owner has already had a security system fitted. Those with older cars should in theory find the answer in their vehicle’s service history record, which ought to detail any such work that has been carried out over the years.

Not having an immobiliser fitted at all is likely to put up your insurance premium. At the same time, insurers will generally offer lower premiums on cars with factory-fitted immobilisers as these tend to be considered as more desirable from a security standpoint. 

What is a Thatcham device?

A Thatcham device is a security device, such as an engine immobiliser or alarm, that has been certified and rated by Thatcham Research, otherwise known as the Motor Insurance Repair Research Centre. 

While Thatcham has been involved in vehicle standards for more than half a century, they have defined the industry benchmark for alarms and immobilisers since the 1990s. 

Thatcham also rates devices such as wheel locking nuts, steering wheel locks and gear lever locks, so the phrase “Thatcham device” can cover quite a wide range of products, aside from just immobilisers and alarms.

Thatcham category 1

Thatcham devices designated as Category 1 refer to the most sophisticated security systems, combining an immobiliser with an alarm. Category 1 devices offer features like ignition and perimeter detection along with movement, tilt and glass break sensors. 

A Thatcham category 1 alarm’s siren will be powered by its own battery supply. Systems in this category must also be automatically set, without the driver’s intervention. 

A car security system, combining an immobiliser and inbuilt alarm, would certainly be less effective if it relied on the driver to remember to set it each day, or it could easily be temporarily deactivated by accident. 

Thatcham Category 2

Security systems designated as Category 2 by Thatcham solely consist of an immobiliser. Immobilisers with this certification must meet the same technical specifications of immobilisers in Category 1. 

All immobilisers with Thatcham certification must isolate at least two circuits or systems, or a minimum of one operationally relevant vehicle control unit with coded intervention. Thatcham immobilisers must be resistant to attack for a minimum of five minutes. 

As with Thatcham alarms, the immobilisers must also be passively set, rather than relying on any human intervention to be activated.

So, what type of alarm and/or immobiliser does your car have? If your car is relatively modern, then it should have been assigned a Thatcham Category 1 or 2. Should you be unsure about your security system, you can easily locate the Thatcham Category on the internet.

Does my car have a Thatcham-approved Category 2 alarm?

Strictly speaking, alarms are not part of Thatcham Category 2, as this is an immobiliser-only category. In common with Category 1, Thatcham only awards the Category 2 certification if certain criteria are met, such as the system being automatically set, without the driver’s intervention. 

You might still be wondering what is a Thatcham-approved alarm?

An alarm can be designated as Thatcham Category 2 or 1 as part of a security system if it is retrofitted in a car already fitted with a Thatcham Category 2 immobiliser.

The strict rules mean the alarm must meet the Thatcham Category 1. Having an alarm added to your existing immobiliser-only Category 2 system could lower your insurance premiums. 

How can I find out what car alarm I have?

If your car is relatively modern you can find out whether it has a fitted car alarm or not through various websites, which display the Thatcham Category information for the make and model of your vehicle. 

For example, if you drive a standard Vauxhall Zafira, it does not have a factory-fitted alarm, but only an immobiliser, being listed as Category 2. However, there are various types of non-standard model Zafira that do have factory-fitted alarms, as these cars are in Category 1, including the Zafira Sri and Zafira Elegance. 

The Toyota Yaris T Sport is Category 1 but the Toyota Auris is Category 2. A simple internet search should quickly answer the question as to what type of alarm and/or immobiliser does your car have. 

Do Thatcham alarms make my car insurance cheaper?

Generally a Category 1 would have a lower insurance premium than a Category 2 vehicle as the more sophisticated security system should mean the car has a lower risk of being stolen. 

However, other factors, such as engine size, repair costs and car values are considered, with insurers assigning higher premiums to more powerful vehicles, as these have been found to be more likely to suffer car accidents. 

This is likely to be relevant as it tends to be the more upmarket versions and models of cars that are in Category 1 as opposed to the more standard ones that are found in Category 2. 

If you are unsure, and if your model falls into Category 2, or it’s an older car and doesn’t fall into either of these categories, you should be able to find out if previous owners have retro-fitted an alarm by checking the car’s service history. 

Another way to test for an alarm is simply by locking the car with the key fob, and then after a short time attempting to unlock your car manually and open a door from the inside. An ear-splitting siren in your ears, and you know you have an alarm!

Having an immobilisers or alarms fitted to an older car

Adding a vehicle immobiliser or alarm to an older car that may not have a security system could reduce your insurance premiums. 

Adding an alarm to a car that only has an immobiliser built-in could make your insurance cheaper and give you greater peace of mind, as your vehicle is made more secure. 

You should also want to reduce the risk of your car being stolen, in which case you may need temporary insurance so you can drive a borrowed car until you can buy a replacement.

It may also be worth considering upgrading your security system even if it’s already Category 1, especially as technology is changing all the time, with car makers constantly adding technical features to stay one step ahead of thieves. 

Always consider regular maintenance of your existing car security systems part of your annual service.

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