As part of the overall drive to reduce emissions, and to comply with the new Euro 6 standards, more and more diesel cars now include SCR (Selective Catalytic Reduction) technology. Used in the right way, SCR can help to reduce Nitrogen Oxide (NOx) emissions by as much as 90%, with fuel efficiency also increasing by between 3% and 5%.

For the technology to work, vehicles need to be fitted with a special tank for storing a liquid-reductant agent known as AdBlue®. So if your vehicle is fitted with AdBlue® there are a few things you’ll need to know:

What exactly is AdBlue®?

AdBlue® is a mixture of water and urea, which you top up periodically, as you do with fuel. As you drive, AdBlue® flows from the tank into the exhaust pipe via a dedicated catalyst. The effect is a chemical reaction that converts most of the NOx molecules into nitrogen and water. This is then released into the atmosphere as steam.

How do I fill up the AdBlue tank?

AdBlue® is available from an increasing number of fuel stations and motorway services, but your dealer will also be able to supply AdBlue®. New vehicles tend to have a filling point next to the fuel cap, however it does vary depending on the manufacturer and model so it’s best to refer to the owner’s manual before you start.

How will I know when it’s needed?

It’s important to take action as soon as you see any relevant warning lights on your dashboard. There are three possible warnings:

First Warning – advises you that the AdBlue® tank is getting low

Second Warning – will give you a mileage range and sometimes is accompanied by an acoustic warning

Final Warning – at this point the vehicle will either go into limp home mode (run at reduced power) or will not restart once the ignition has been switched off.

Who pays for the AdBlue®?

Because it’s a solution you top up periodically, as you do with fuel, the costs are not covered by the maintenance contract and are therefore payable by the driver of the vehicle. The only exception to this is if the service schedule states that the fluid needs to be changed(rather than topped up).