The Diesel Volkswagen is in deep trouble right now. The company which owns roughly 70 percent of US Passenger car diesel market is in scandal due to cheating on the diesel-emission test. They are well known in promoting "Clean Diesel" over the years. 

What happened was Volkswagen have installed an emissions software on more than half million cars all over the US. Almost 10.5 million more worldwide. This emissions software allows the sedan to sense the unique parameters of emissions drive cycle set by an Environmental Protection Agency. Environmental Protection Agency and California Air Resources Board announced these so-called "defeat devices", a device that could detect steering and throttle. 

They also have other input devices that could be used in the test to switch between two distinct operating modes. In all the test conducted, Volkswagen was fully compliant with all federal emission levels.

The tricky scheme was in normal driving. The Diesel Volkswagen's computer initiates a switch to separate mode. This significantly changes the fuel pressure injection timing, exhaust gas recirculation, and, in models with AdBlue, the amount of area fluid sprayed into the exhaust. 

While the sedan is in this mode, it is most likely to deliver higher mileage power to the car. It also allows heavier nitrogen oxide emissions (NOx), a smog-forming pollutant linked to lung cancer, up to 40 times higher than the federal limit. The result sometimes varies.

The following are the vehicles that have failed the emission tests. The 2009-2015 Volkswagen Jetta 2.0L TDI, 2010-2015 Volkswagen Golf 2.0L TDI, 2012-2015 Volkswagen Beetle 2.0L TDI, 2012-2015 Volkswagen Passat 2.0L TD, 2009-2016 and the Volkswagen Touareg 3.0L V-6 TD.

The test was conducted by the Environmental Protection Agency. Aside from Volkswagen, Audi and Porsche diesel models have been cited by the EPA for emissions violations. The issue may prevent car owners from renewing their contract with Dieseled Volkswagen sedans if issue won't get fix.

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