Even if Volkswagen is the only one to have recognized a faking of the emissions of its diesel models, Mercedes was very early suspected of doing the same. A new report accuses the brand at the Star of having implemented 8 software programs to reduce the efficiency of emission control systems on an E-Class.
In the so-called “dieselgate” affair, Volkswagen is not the only one to have been splashed. Mercedes is also one of the manufacturers who were quickly singled out for this environmental scandal. With, as a climax, the obligation to recall no less than 774,000 vehicles in 2018, on the order of the German transport ministry, the KBA. But unlike its compatriot, the Star brand has never admitted to having deliberately rigged the emissions of some of its models. So far, we remained at the stage of suspicion, supported by excessive pollution measures on specimens tested in actual use. A situation that a report by automotive computer expert Felix Domke, commissioned by the international law firm Milberg, could turn upside down.
Six software for the only anti-NOx catalyst
Made public by the German association for the defense of the environment Deutsche Umwelthilfe (DUH), this 32-page document indeed reveals the presence of eight “cheat software” on an old-generation E-Class 350 BlueTEC 4Matic Break, registered for the first time in January 2016 and conforms to the Euro 6 standard. Six of these software programs would reduce the efficiency of the SCR catalyst, responsible for fighting against dangerous nitrogen oxides (Nox) by transforming them into nitrogen and water, harmless , with the help of a liquid called Adblue. As for the other two, they would act on an older pollution control system, the famous EGR valve. All are activated according to different parameters: volume of exhaust gas or NOx at a given time, temperature of the intake air or inside the SCR, AdBlue consumption, etc.
Too often degraded operation
In their defense, manufacturers often claim that they are obliged to do so to protect the reliability of their engines in certain cases, such as in very hot or very cold weather. But Felix Domke’s report says that this degraded operation of anti-pollution systems occurs far too often.
“Even under normal driving conditions, there is almost always at least one defeat device that will prevent the reduction of pollutant emissions, even if it is not necessary for physical reasons or for engine protection, explains L ‘expert. This significantly reduces the amount of AdBlue that is injected, whereas it would take much more to neutralize the Nox in the SCR catalyst.“
As a bonus, three of these softwares incorporate an “age factor” which lowers their triggering threshold as soon as the catalyst reaches a certain wear. A milestone that can be reached very quickly, since 1% wear is enough for two of them! Finally, the document also denounces a tendency to “hysteresis”: even when conditions have returned to perfectly normal, it sometimes takes a long time for the SCR or the EGR valve to resume their maximum efficiency.
TO READ. Dieselgate: Volkswagen would still use software that increases NOx
A Mercedes parade already prepared?
To arrive at all these conclusions, Felix Domke relied primarily on an analysis of the ECU (electronic control unit), the “brain” which controls the operation of the engine. A job far from simple, because this organ, here provided by the Bosch equipment manufacturer, is capable of emitting more than 10,000 different signals. In addition, the manufacturers are not really willing to reveal all the secrets. The expert therefore had to use his 20 years of experience in software development and use various tools to circumvent these obstacles. In return, to simplify the task a little, the study here relied on a single vehicle, which is sure to arouse some criticism. In fact, Mercedes may already be preparing its answer, after being surprised to carry out on-road emissions tests with some of its older models this summer. Including an E-Class of the same generation and a G-Class equipped with the same OM642 V6 diesel.
A recall of all vehicles requested
For the DUH association, however, these conclusions can apply to all vehicles with the same engine. ” Felix Domke’s report finally proves that Daimler is guilty, ensures its director in Germany, Jürgen Resch. It shows us for the first time how the company manages to meet legal limits in laboratory tests, while literally flooding our cities with harmful nitrogen oxides ”.
“The handling of pollution control systems is not linked to physical reasons or to engine protection, continues Jürgen Resch. The reason is as simple as it is cynical: to maximize profits at the expense of the environment and the health of city dwellers.“
The organization reports an increase of up to 500% in NOx emissions between certification tests and actual use conditions. It therefore asks the German federal government to recall all vehicles still equipped with this software, in order to deactivate them. A measure which would, according to the report, above all for the consequence of more than doubling the consumption of AdBlue. Not necessarily ideal at a time when the prices of this additive are on the rise. But that would apparently be the only real price to pay for drastically lowering NOx emissions. As for the law firm Milberg, sponsor of this study, it unsurprisingly invites the owners of the vehicles affected by this cheat to approach it to claim compensation from Mercedes. An approach that joins that already initiated by the Dutch foundation Diesel Emissions Justice in June 2020.
