How Mileage Blockers Work

What Is a Mileage Blocker?

A mileage blocker, also called an odometer stopper or CAN blocker, is a small module that fits behind your instrument cluster (the clocks). It’s designed for off-road use, track days, dyno testing and diagnostics, where you don’t want test miles added to the odometer.

Every Autotech UK blocker is programmed for your exact vehicle and tested in our UK workshop before it ships.

How It Works, Step by Step

1. It plugs in behind the clocks

   The blocker connects between the instrument cluster and its original plug, so nothing is cut or rewired.

2. It reads the vehicle’s signals

   Modern vehicles share information such as speed and distance over a network called the CAN bus. The blocker sits on that connection and passes messages through.

3. Switched on, it pauses the odometer

   While it’s active, the distance information the odometer counts is held back, so the mileage stops going up. Depending on the mode, the speedometer and driver-assistance systems keep working.

4. Switched off, everything is normal

   Turn it off and every message passes straight through, so the vehicle records mileage exactly as it did before.

Watch It Being Fitted

Here’s one of our blockers being fitted to a Land Rover Defender.

More fitting videos for other makes are on our YouTube channel.

Blocking Modes

Most of our blockers have several modes, so you can choose how much mileage is recorded and whether the speedometer keeps working. The exact modes depend on your vehicle and are listed on its product page. A typical set looks like this:

• Full block Almost no mileage is recorded. On some vehicles the speedometer stops working in this mode.
• Partial block Only part of the mileage is recorded, for example 30% to 40%, and the speedometer keeps working.
• Off The blocker passes everything through and mileage records normally.

Switching It On and Off

• Change modes by holding the BC button for 10 seconds, or use our smartphone app (sold separately).
• You can switch modes at any time, even while driving.
• The blocker always remembers its last setting.
• There are no warning lights or error messages when it’s active, and no mileage jump after it’s removed.

Fitting and Removal

Our blockers are plug-and-play: they use the vehicle’s original plug, with no cutting or soldering. Each one comes with step-by-step fitting instructions, and we offer free video-call help on WhatsApp if you get stuck. Prefer us to do it? Choose fitting at checkout and our mobile fitter will come to you, at home or work, anywhere in the UK.

To remove it, unplug the blocker and reconnect the original plug. For many vehicles you can also choose our long cable with a quick-release plug, so you can remove it in seconds without taking the dashboard apart again.