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21 May 2020
Jamie Gibbs Jamie Gibbs

How engine immobilisers, alarms and trackers affect your car insurance


Thief trying to disarm car security

Beefing up your security could help you keep your car insurance prices low - but what security features are available?

Whenever you look at a list of tips to lower your car insurance costs, one that crops up a lot is "make sure you beef up your security with an immobiliser and alarm".

That's all well and good, but what's the difference between them?

READ MORE: Top tips for cheaper car insurance

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What is a car engine immobiliser?

An engine immobiliser is a device that only allows your car to start by using the correct key or fob. This means that your car is protected against hotwiring from would-be thieves. 

Does my car have an immobiliser?

Immobilisers have been compulsory in new cars since October 1998. So if your car was made after this year, you’ve got one.

For cars older than this, you’ll need to check. Some might have been fitted with an immobiliser at the factory, and others might have had them installed later.

The easiest thing to do is check your owner’s handbook. It’ll say if your car has a factory-fitted immobiliser.

What is a Thatcham device?

Thatcham is an independent institution that rates car security, and helps car insurance companies to factor this into their price calculations.

Thatcham has seven different classes for car security – the closer to first class you get, the more robust your security is. 

READ MORE: Thatcham security safety rating

Class 1 – electronic alarm and immobiliser

The most complex and secure system on the market. Class 1 alarms often run on their own battery supply, and immobilisers have the ability to activate on their own.
Both immobiliser and alarm have to be present for class 1.

Class 2 – electronic immobiliser

This is a class 1 engine immobiliser but without the alarm. For class 2, it needs to be able to disable two of the three systems used to drive the car.

Class 2/1 – electronic alarm upgrade

If you have an immobiliser, you can add a class 1 alarm afterwards. Though this doesn’t push you into fully-fledged class 1 territory, it’s as close to it as you’ll get without getting a new car.

Class 3 – mechanical immobiliser

The most common kind of class 3 feature is a steering wheel lock. Class 3 features disable only one of the three systems used to drive a car. These must be fitted every time you want to secure the car.

Class 4 – wheel locks

If you’ve got a set of shiny alloys, you’ll likely have wheel-locking nuts on them. These nuts can only be removed using a special key, making them harder to steal.

Class 5 – post-theft tracking 

If your car is stolen, this system tracks its position so that the police can recover it. They also have the ability to immobilise the car remotely.

Class 6 – tracker

This is a class 5 tracker but without the ability to remotely immobilise the car.

Class 7 – tracker

A more simplistic version of a class 6 tracker that allows police to recover a stolen car.

There’s also a Q class that covers aftermarket security upgrades that don’t fall into classes 1-7. This includes locks and alarms that aren’t approved by Thatcham.

How do alarms and immobilisers impact my car insurance policy?

The higher the level of security you have, the more difficult your car is to steal – or at least the bigger a deterrent it becomes.

This means your car is safer, and should go some way to giving you a lower car insurance price.

If you want to beef up your security even more, consider keeping your car in a garage overnight. You can also take a look at our tips on lowering your car insurance costs.

READ MORE: Car insurance policy types


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