What is AdBlue?

AdBlue® is a diesel exhaust fluid (DEF) mixture used in all heavy-duty diesel engines produced after January 1st, 2010 and most commercial vehicle and car diesel engines made after September 2015 – primarily Euro 6-compliant models. AdBlue® is not a fuel additive as it’s added to the exhaust gas after combustion has taken place.

AdBlue® reduces Nitrogen Oxide (NOx) emissions. Nitrogen oxide is a harmful gas that can damage the human respiratory system, reducing lung function, increasing allergen exposure and the risk of respiratory illnesses. It promotes the formation of fine particulate pollution and ground ozone – harmful to both health and vegetation.

It’s for these reasons that governments set limits on vehicular NOx emissions and promote the use of AdBlue®. This improves air quality and reduces the danger of diesel pollution-related illness and death.

The term AdBlue® is a worldwide trademark of the German Association of the Automotive Industry (VDA) relating to DEF produced in accordance with the ISO 22241 specifications.

What is AdBlue made of?

AdBlue® is made of a colourless mixture of high-purity urea (32.5%) and deionised water (67.5%), as set out in the ISO 22242 standard. Urea contains ammonia; the active ingredient in AdBlue® that reacts with NOx and neutralises it before it enters the atmosphere.

What does AdBlue® do? How does it work?

AdBlue® works alongside vehicle engine selective catalytic reduction (SCR) systems to reduce nitrogen oxide (NOx) exhaust emissions. Vehicles that use the active emissions control technology can usually be identified by the use of ‘SCR’ or ‘Blue’ in their model names.

After exhaust gas passes through the diesel particulate filter, AdBlue® DEF is sprayed and mixed into it via a dosing control system as it enters the SCR catalytic converter. Here, the ammonia within the urea reacts with NOx in the exhaust stream, neutralising it to form harmless nitrogen (N2) and water vapour (H2O), while additionally reducing total fuel consumption by 2-6%.

AdBlue and SCR systems are highly effective, reducing NOx emissions by up to 90%, hydrocarbon and carbon monoxide emissions by 50-90%, and particulate emissions by 30-50%.