Volkswagen used software that circumvents emissions testing for certain air pollutants, according to the EPA, which issued the automaker a notice of violation of the Clean Air Act on Friday and ordered VW to recall almost half a million cars on the road.
The notice of violation alleges that four-cylinder Volkswagen and Audi diesel cars from model years 2009-2015 include software that circumvents EPA emissions standards for certain air pollutants.
California is separately issuing an in-use compliance letter to Volkswagen, and the EPA and the California Air Resources Board have both initiated investigations based on Volkswagen’s alleged actions.
As described in the notice, a sophisticated software algorithm on certain Volkswagen vehicles detects when the car is undergoing official emissions testing, and turns full emissions controls on only during the test. The effectiveness of these vehicles’ pollution emissions control devices is greatly reduced during all normal driving situations. This results in cars that meet emissions standards in the laboratory or testing station, but during normal operation, emit nitrogen oxides, or NOx, at up to 40 times the standard.
The software produced by Volkswagen is a “defeat device,” as defined by the Clean Air Act.
The EPA and CARB uncovered the defeat device software after independent analysis by researchers at West Virginia University, working with the International Council on Clean Transportation, a non-governmental organization, raised questions about emissions levels, and the agencies began further investigations into the issue.
In September, after EPA and CARB demanded an explanation for the identified emission problems, Volkswagen admitted that the cars contained defeat devices.
VW may be liable for civil penalties and injunctive relief for the violations alleged in the notice. The allegations cover roughly 482,000 diesel passenger cars sold in the United States since 2008.
Affected diesel models include: