In case you were wondering when the supplier who provided Volkswagen’s cheat-ridden engine management software would come under fire, Reuters reports that United States federal prosecutors are investigating supplier Robert Bosch GmbH’s role in the dieselgate scandal.

According to Reuters, Bosch provides the EDC17 engine control module and other basic software for almost all the four-cylinder diesel engines sold in North America, including models by Volkswagen, BMW and Mercedes-Benz. Those systems control how vehicles clean spent fuel before releasing it as exhaust.

How systems are used in different vehicles, Bosch told Reuters, is the responsibility of the automaker. Volkswagen in particular asked for their systems to turn on the emission control system when the cars were being tested in a lab, but not when the cars were used on the road. Earlier reports say that Bosch warned Volkswagen not to use the test mode on production vehicles — a warning that went unheeded.

Now the United States Department of Justice wants to know how pervasive the cheating was at Volkswagen and its suppliers: who knew that the software was being used in illegal ways, and who merely did what they were asked. Reuters explains:

For authorities to bring charges against Bosch, they would have to prove the supplier knew that their technology was being used by Volkswagen to evade emissions requirements, said Daniel Riesel, an environmental attorney at Sive, Paget & Riesel P.C.

“If you know that a crime is being committed and you actively facilitate part of the crime you are on the hook,” Riesel said. “A garage mechanic who soups up a car so a bank robber can make his getaway is participating in the crime.”


Per Reuters, the investigation is in its preliminary stages and no evidence of foul play has been discovered by U.S. prosecutors at Bosch so far. It remains unclear how much Bosch knew about Volkswagen’s use of their test mode, and how closely Bosch worked with Volkswagen in the test mode’s development.

Bosch, Volkswagen and the Department of Justice declined to comment to Reuters on this particular investigation.

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