The EPA and the DOJ allege that Detroit Diesel, a Daimler unit, sold diesel engines for model year 2010 trucks and buses that did not have valid EPA-issued certificates of conformity (CoC). Since some of those 7,786 engines were used in school buses, some of the money Detroit Diesel will have to pay will be used to, "improve air quality inside school buses by reducing exposure to diesel exhaust," according to the EPA. For years, the EPA has wanted to clean up dirty diesel school buses, in part because traffic exhaust can cause asthma in children.
Detroit Diesel Corp. to reduce exposure to harmful diesel exhaust under our latest Clean Air Act settlement. https://t.co/wWhiBSR5dd— U.S. EPA (@EPA) October 6, 2016
The details of the complaint are a bit technical, and come down to timing. Detroit Diesel had CoCs for 2009 model year vehicles, but since it kept making those engines in 2010 - when stricter rules were in effect - the engines were not legal for sale. This penalty is an attempt to make things right. The public will be able to follow the progress on a website that Detroit Diesel will have to set up and share its data.