AdBlue: do you know when you need to fill up this additive's tank?

AdBlue has become essential for many drivers who have opted for a diesel vehicle. AdBlue is an additive made of deionised water with a 32.5% urea solution. This liquid is harmless to the environment and allows diesel engine exhausts to considerably reduce NOx emissions when they reach the atmosphere. It should be noted that AdBlue is colourless, odourless and free of toxic products.

The chemical reaction that takes place when AdBlue is applied is called Selective Catalytic Reduction (SCR) and the result is a mixture of nitrogen and water vapour. This mixture is much less harmful to the environment and allows emissions to comply with the Euro 6 standard, which came into force in 2014.

Where AdBlue is stored

If you are a diesel car user, you will already know how to use and refuel AdBlue, but if you have always driven a petrol car, you will come across something completely new that may cause confusion. Because AdBlue is a concept that does not exist in petrol cars and needs to be understood when switching to a diesel car.

All modern diesel cars have an AdBlue tank that allows emissions to be reduced with this additive. This tank can hold between 12 and 18 litres, although this may vary depending on the make and model. This capacity provides a range of between 3,000 and 10,000 kilometres, but these figures depend on many factors.

The car gives a warning when AdBlue is running low in the tank. This warning usually shows the remaining range based on the tank’s contents, so the driver can work out how far they can travel without refuelling AdBlue.

What happens when AdBlue runs out? In principle, nothing interferes with the normal operation of the engine, so it keeps running without problems. But once it stops, the engine will not restart. So you need to know when to refuel AdBlue to avoid being stranded in the middle of a journey.

AdBlue range warnings

Generally, the AdBlue range warning comes in the form of a warning light on the instrument panel, and the on-board computer shows how many kilometres can be covered with the amount remaining in the tank. Many petrol stations have an AdBlue pump, so you only need to drive the car up to it and fill the tank.

It is important to know that many diesel vehicles only accept a top-up of more than 5 litres, so this should be taken into account. Even if you add one or two litres, it will not be enough and the vehicle will request that minimum amount. There is no need to worry about the cost, as a litre of AdBlue costs less than one euro, so filling the tank will not be a major expense.

It is important that the AdBlue tank always contains a sufficient amount of liquid to cover the journey you need to make. The best approach is that each time you top up the tank, you fill it completely. This provides several thousand kilometres of range and means you can forget about it for quite a while.