AdBlue is a liquid solution used to reduce NOx (or nitrogen oxides) emissions from diesel engines. AdBlue is injected into the exhaust system between the engine and the SCR catalyst and converts the nitrogen oxides to nitrogen and water. As a result, you therefore have lower NOx emissions.
In this article, we take a closer look at what exactly AdBlue is.
What is AdBlue
As explained above, AdBlue is an aqueous solution added into the engine system. AdBlue is a mixture of demineralised water and pure urea
Not all passenger cars are equipped with one; your car must have an SCR system. SCR stands for 'Selective Catalytic Reduction' or Selective Catalytic Reduction. These are mainly Euro 6 diesel engines. From 2014, this system was introduced in trucks but from 2014 onwards also in several passenger cars. Several models of various brands use SCR catalyst such as Audi, BMW, Citroën, Ford, Mazda, Opel and Peugeot, for example.
How can I refill AdBlue?
Where you can refill AdBlue varies from car to car, sometimes the filler cap is next to the Diesel filler cap but sometimes it is under the bonnet. Not sure? Check your car's manual! It is often a blue screw cap with the text AdBlue on it.
You can refill AdBlue yourself, simply buy a jerry can of AdBlue and fill the reservoir. Just twist off the cap and pour. AdBlue is often available in 5- or 10-litre containers and available from various (online) shops. Buy AdBlue can easily be done at this webshop, for example.
When should I refill it?
If your car has an SCR system, there is probably a gauge in the car where you can see the level of AdBlue. Keep a close eye on the gauge and top up AdBlue as soon as the level gets too low.
If you have scheduled a service for your car, the mechanic in the workshop will often also check the level and top it up where necessary. If the AdBlue tank becomes empty, however, you should refill it yourself in time, make sure there is always enough fluid in the tank but don't overfill the tank. This is because if you pour too much of the fluid into the tank, it can overflow. You then have the chance that the liquid will crystallise, clogging the reservoir's filler neck. So stop filling the tank in time. If in doubt, we always recommend having it refilled by a specialist garage in your area.
Storage advice
Remember to store AdBlue at room temperature and in a dark place as the product can freeze at -11 degrees celcius and its composition can change due to exposure to UV light. So store it in a dark place and not too cold.
Nitrogen oxides?
Nitrogen oxides (NOx) are mainly released during combustion processes, where oxygen (O2) and nitrogen (N2) from the air react with each other. These combustion processes take place particularly in vehicles with diesel combustion engines. NOx is particularly harmful to the environment and is, for example, 40 times more toxic than carbon monoxide (CO) and 4 times more dangerous than nitrogen monoxide (NO).
By adding AdBlue, a chemical process occurs that reduces emissions of nitrogen oxides by up to 80% by converting much of it into nitrogen and water.
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