Whoops: Mercedes-Benz Diesel Probe in U.S. Uncovers Possible Defeat Device

Matt Posky
by Matt Posky
whoops mercedes benz diesel probe in u s uncovers possible defeat device

U.S. investigators have found what could be illegal software modifications on Mercedes-Benz diesels intended to help the vehicles pass emissions testing. An engine management function called Slipguard recognized whether the car was undergoing testing procedures while another, called Bit 15, halted emissions cleaning after roughly 16 miles of driving. Together, the two pieces of software may amount to what is known within the industry as a “defeat device.”

When paired the software apparently enabled the cars to produce NOx levels up to 10 times higher than what is legally permitted. Interestingly, Mercedes-Benz issued a voluntary recall upon roughly 3 million European cars last month to reduce nitrogen oxide emissions by tweaking their electronic control units.

German media outlet Bild am Sonntag, has also cited confidential emails between Mercedes’ engineers that questioned whether the software functions were legal to use. Daimler has been under pressure in the diesel exhaust scandal for some time. Stuttgart prosecutors and the U.S. Department of Justice have both been investigating the issue since the spring of 2017.

A company spokesman declined to elaborate on the documents, saying the automaker was cooperating with the U.S. authorities and had agreed upon strict confidentiality with the Department of Justice. “The authorities know the documents and no complaint has been filed,” a spokesman told Automotive News. “The documents available to Bild have obviously selectively been released in order to harm Daimler and its 290,000 employees … We have been fully cooperating for more than two years and provide comprehensive transparency.”

Daimler CEO Dieter Zetsche has repeatedly emphasized, since the outbreak of Volkswagen’s diesel sandal over two years ago, that vehicles from Mercedes-Benz had not and would not be manipulated.

[Image: Mercedes-Benz]

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  • Land Ark Land Ark on Feb 19, 2018

    I always suspected that no other manufacturer called out VW for their cheat devices before the private company did because they were [mostly] all doing it. Everyone was baffled by how VW was able to get the numbers that they did. You can't tell me someone didn't reverse engineer a car and figure it out. Also suspiciously absent were other car makers trying to lure customers to them assuaging that their clean diesel was actually clean.

  • MercedesDieselGuy72 MercedesDieselGuy72 on Feb 19, 2018

    Rude comments above aside, I've owned several M-B diesels, several of which went well past 300K miles, one that went to just under 500K before being totaled in a street flood. Currently in one of the apparently cheating E250 Bluetec 4-matic. I buy them because they get great mileage, are very very comfortable, I travel long distances often, and the Diesel engines last much longer. I am disappointed about this news, but... I will drive them until I cannot.

  • FreedMike I'll welcome as many cars like this as I can, but I think Acura's "right move" was to put the Accord Sport's 2.0T in the base model and sell it for thirty-five or so. That's a pretty compelling performance / value proposition.
  • Wjtinfwb I'll certainly admit to a bit of nostalgia that drives my appreciation for these 70's yachts, but there's more to it than that. It was an era that the Big 3 ruled the luxury market with the German's and British nothing but a beer fart in the marketplace. That changed drastically as the early '80s crept in but in 1977, a Mark V or Seville was where it was at. No rose colored glasses, they were not great cars, what they were was a great living room that you could ride to the office in. I grew up on a diet of Cadillac's, Lincoln and one big Chrysler before dad made the move to a 280SE in about '77. Impeccably built and very road worthy, dad initially didn't like the firm seats, clunky automatic transmission and very weak A/C. The exorbitant maintenance costs didn't help. But he enjoyed the driving characteristics enough to get another Benz, then a 733i, an Audi 5000S and a Jag XJ6. Compare these to today's Cadillac's (non- V) and Lincoln's that with the exception of the Escalade and Navigator, are boring and probably even more pedestrian than the Eldorado, Seville and Mark's were.
  • FreedMike I was lucky enough to grow up in a household with the two best German luxury sedans of the time - a manual '81 733i, and a '75 Mercedes 450SE. The BMW was a joy on back roads, and the Benz was a superb highway car. Good times. And both were dramatically better than the junkheap American luxury cars Dad had before.
  • Wjtinfwb A Celebrity Diesel... that is a unicorn. Those early A-bodies were much maligned and I'm sure the diesel didn't help that, but they developed into very decent and reliable transportation. Hopefully this oil-burner Chevy can do the same, it's worth keeping.
  • Wjtinfwb After S-classes crested the 40k mark in the early '80s, my dad moved from M-B to a BMW 733i Automatic. Anthracite gray over red leather, it was a spectacular driving car and insanely comfortable and reassuring on long interstate hauls. My mom, not really a car person, used the BMW to shuttle her elderly Mom back home to Pennsylvania from Miami. Mom and grandma both gushed with praise for the big BMW, stating she could have driven straight through the car was so comfortable and confidence inspiring. A truly great car that improved through the E38 generation, at which point the drugs apparently took hold of BMW styling and engineering and they went completely off the rails. The newest 7 series is a 100k abomination.