For diesel engines, AdBlue was first presented as a lifeline. Thanks to this “miracle product”, which mixes 32.5% urea and 67.5% mineralized water, car manufacturers have been able to meet ever stricter anti-pollution standards. By injecting this substance upstream of a specific catalyst, called SCR (Selective Catalytic Reduction), it became possible to transform the dangerous nitrogen oxides (Nox), the Achilles heel of “fuel oil”, into harmless nitrogen ( N2) and water vapor. Initially competing with the Nox trap, simpler and less expensive but also less effective, this technological solution ended up becoming widespread over the last ten years on passenger vehicles powered by diesel. But if it is formidable in its effectiveness in the laboratory, its use in “real life” has shown that it does not only have advantages for motorists. Now that we have several years of hindsight, we can even wonder if AdBlue did not help to sink a diesel engine which continues to lose speed in Europe…
Numerous reliability problems
The main problem posed is undoubtedly that of reliability. Discontent has in fact continued to grow over the years, especially as several consumer associations have taken up the issue, in France, Italy and Belgium. Most often, it is the tank that requires replacement. The fault, in particular, lies in a natural phenomenon: the crystallization of AdBlue. This liquid can in fact tend to solidify in very cold weather (- 10°), but also in high heat (30-35°), especially if the vehicle remains immobilized for a long time. This can lead to the tank cracking or corroding. In more severe cases, AdBLue injectors may also be damaged. The bill can therefore range from a few hundred to a few thousand euros, at fairly low mileage, and coverage is not systematic.
The Stellantis group, notably Peugeot and Citroën, seems to be one of the most affected by these problems. The company has also agreed to compensate Italian owners of diesel models and the Belgian consumer association Test Achats has put it on notice to do the same across the Rhine. But other manufacturers, such as Renault-Dacia, Volkswagen and its various subsidiaries, Mercedes and BMW are also affected. in seemingly less significant proportions. Whatever your car, don't hesitate to send us your testimonials to the address [email protected] if you encounter reliability problems linked to AdBlue. We will return to this hot topic in more detail soon.
Constraints on use
Even when it works perfectly, the SCR system also creates certain constraints in use. It involves regularly filling up with AdBlue, stored in an additional tank. In general, the operation is quite simple and does not come up too frequently. Very often, there is no need to top it up yourself: it is possible to let the mechanic take care of it during your service. But that increases the bill and it also happens that a message lights up on the dashboard before this deadline to indicate that AdBlue will need to be refilled fairly quickly. In this case, even if the vehicle still leaves a margin of at least several hundred kilometers, it is not possible to ignore the warning for too long. The standards are strict on the subject: your car will refuse to start if the tank containing the anti-Nox fluid is dry. Revised upwards in recent years, to take into account the tightening of anti-pollution rules, AdBlue consumption can vary quite significantly depending on use. TotalEnergies cites a range between 1 and 3 l per 1,000 km. Waiting for the periodic review will therefore not always be possible.
Filling up with AdBlue is not always easy
To avoid being stranded, you will sometimes have to fill up the additional tank yourself, which is not always possible at the pump. The guns that allow the filling of this substance are not found in all service stations, and some of them are reserved for trucks… although it is still possible to use them for certain car models. In certain cases, however, the only solution will be to purchase a container, with a less favorable price per liter. Fortunately, the AdBlue tank opening is most often quite accessible, right next to that of the diesel tank. But it also happens that it is located under the trunk floor or under the hood, and this constraint remains poorly experienced by many motorists. Even if the liquid is harmless, it is never pleasant to have to struggle with a container that is a bit heavy and not always well designed. As a bonus, it is sometimes necessary to go to the workshop despite everything to reset the on-board computer and eliminate the alert message.
A significant additional purchase cost
Finally, AdBlue does not just slightly increase the cost of use. SCR technology, which is quite expensive, has also contributed to increasing the gap between the selling price of a gasoline vehicle and that of its diesel equivalent. However, examples are becoming more and more difficult to find, as diesel fuel is becoming increasingly rare in the ranges today. It is even becoming complicated to find a French model that still offers this choice, apart from utility vehicles. Among versatile city cars, the Renault Clio acts as the last of the Mohicans with its very successful 1.5 Blue dCi 100. But the additional cost of €2,200 with identical equipment compared to the 1.0 Eco-G 100 will take an extremely long time to amortize despite much lower fuel consumption, especially since the gasoline engine here is also LPG compatible.
The demonstration remains valid for most vehicles on the market. A 163 hp BMW This clearly did not do the business of diesel, which has also had to endure an increasingly hostile political climate towards it since the outbreak of the dieselgate scandal at Volkswagen. Sales of vehicles powered by diesel continue to collapse in Europe, the only continent historically favorable to this fuel, to barely fall above 10% market share in September 2024. A hell of a chasm compared to the 55% they reached in 2011.
Diesel car sales collapse in Europe
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