Diesel

Have Defeat Devices Been Discovered In Mercedes Diesels?

The scandal that doesn't want to die.

In the aftermath of the Volkswagen dieselgate scandal, U.S. regulators have cracked down on diesel emissions by further investigating diesel vehicles beyond previously accepted testing processes. Now it seems Mercedes-Benz may get caught up in the turmoil for adding a “defeat device” in the engine management software of vehicles previously sold in the United States that alters the behavior of their emissions systems.

According to German paper Bild am Sonntag (via Automotive News) citing emails from Daimler’s engineers, company employees were questioning whether two engine management functions could be considered defeat devices. US investigators found two functions. The first function is called “Slipguard,” and can recognize when a car is being tested in a laboratory setting. The second function has to do with AdBlue fluid, the liquid used to clean diesel exhaust emissions. Called “Bit 15,” this function would dial back the amount of AdBlue fluid used for exhaust treatment after the car had driven approximately 16 miles.

Together, the functions contributed to Mercedes-Benz diesel cars emitting NOx pollutants up to 10 times higher than legally permitted, the Bild said. Mercedes-Benz’s parent company Daimler didn’t offer official comment on the documents to Bild. A spokesperson for the company stated, "The authorities know the documents and no complaint has been filed. The documents available to Bild have obviously selectively been released in order to harm Daimler and its 290,000 employees." Diesel emissions have come under increased scrutiny ever regulators caught Volkswagen, Audi, and Porsche—all brands of Volkswagen Group—flouting emissions laws in the United States by using “defeat” devices in engine management software.

Some 580,000 Volkswagen vehicles in the US that used the software could emit up to 40 times the legally allowed emissions, but appeared clean when tested by regulators. Daimler has since given up on selling diesel-powered vehicles in the United States. Ola Kallenius, Head of R&D for Mercedes Car Group, said during the 2018 North American International Auto Show in Detroit, “The diesel doesn't fit into our portfolio in the U.S."

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