DETROIT/WASHINGTON: A popular diesel engine management program used by several top automakers, including Volkswagen AG, was not preprogrammed to detect when a vehicle was undergoing laboratory emissions testing, according to the US Environmental Protection Agency and a former EPA official.
Instead, VW had the engine software modified to turn on the vehicle's emission control system when it was being tested in the lab, on a rolling test bed called a dynamometer, then turn it off when the vehicle was on the road, the EPA said.