Volkswagen ordered an external investigation after U.S. regulators found software the carmaker designed for diesel cars gave false emissions data.
The EPA said Friday the software deceived regulators measuring toxic emissions, adding Volkswagen could face fines of up to $18 billion as a result.
The company said it was fully cooperating with U.S. government agencies, and has ordered an external investigation of this matter, being very sorry for having broken the trust of the customers and the public.
The EPA said the cars in question "contained software that turns off emissions controls when driving normally and turns them on when the car is undergoing an emissions test. The feature, which the EPA called a "defeat device," masks the true emissions only during testing and therefore when the cars are on the road they emit as much as 40 times the level of pollutants allowed under clean air rules meant to ensure public health is protected.
The EPA has also refused to grant VW a “certificate of conformity” to sell 2016 model diesel cars with 2.0-liter diesel engines. Because diesel models can account for 20 to 25 percent of the VW brand's U.S. sales each month, the ban is expected to put a major dent in the company's volume and slow its turnaround efforts in coming months.