Mileage blockers: What do they do? And are they illegal?

Knowing the mileage a vehicle has travelled is important for many reasons.

Whether you are buying or selling a vehicle, or you are looking to take your car for its MOT or service – this information is something all drivers should be aware of.

This guide looks at mileage counters – and why mileage blockers have been commonplace in the news in recent months.

What are mileage blockers?

Also known as mileage freezers, mileage blockers are small attachments or devices that can be fitted to certain makes and models of vehicles to electronically pause a vehicle’s odometer.

This means that a vehicle could display fewer miles than it has actually travelled.

If you are buying a car, one of the main things you look for is how many miles it has travelled – and this device can help provide false information and scam people for a higher price.

Why are they back in the news in 2024?

Drivers looking to take their car for an MOT or service may have vehicles with incorrect information on their documents.

Although these devices are more popular around the world, they have been used in the UK and a number of businesses are now selling them to ‘fully qualified technicians’.

They should be used ‘for off-road or research use only’ – but scammers can use these to command a higher price for selling a vehicle.

A simple Google search will display adverts for these devices that state they are almost undetectable.

• How often should I service my car?
• My fuel light came on – how many miles can I go?
• How to spot a clocked car

How do mileage blockers work?

Mileage blockers are small devices that are installed into a vehicle’s on-board computer.

The blockers interrupt the signals that are sent to the sensors that track mileage, meaning that the counter doesn’t increase.

There are several sensors in the wheels and engine control unit (ECU) that tracks this information.

Each manufacturer will have slightly different sensors and ways the mileage is tracked.

Are mileage blockers illegal?

When it comes to the use of mileage blockers, it is not illegal to alter the data on a vehicle in the UK.

However, under UK law it is illegal to not disclose any known mileage discrepancies when you are selling a vehicle or providing official documents at an MOT or service.

Also, citizens can be arrested for mileage fraud under the Consumer Regulation Act.

What is mileage count?

Mileage count is the technology that tracks the distance your vehicle has travelled.

This information is used for legal documents and when you take your vehicle for its MOT or service.

Mileage correction tools

This is similar to a mileage blocker, but it is a piece of software that is installed into the vehicle’s computer.

Much like the blocker, if you do not disclose any tampering with mileage, you will be breaking the law.

If you have any questions about mileage blockers, leave them in the comments below.