The Volkswagen emissions scandal (also known as "emissionsgate" or "dieselgate") erupted on 18 September 2015, when the United States Environmental Protection Agency (EPA) issued a notice of violation of the Clean Air Act to German automaker Volkswagen Group after it was found that Volkswagen had intentionally programmed turbocharged direct injection (TDI) diesel engines to activate certain emissions controls only during laboratory emissions testing. The programming caused the vehicles' NOx output to meet US standards during regulatory testing but emit up to 40 times more NOx in real-world driving.[12] Volkswagen put this programming in about eleven million cars worldwide, and in 500,000 in the United States, during model years 2009 through 2015.[13][14][15][16]