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A diesel whodunit: How software let VW cheat on emissions

Lucas Mearian | Sept. 24, 2015
A software development audit trail will likely point to who authorized the emissions-cheating algorithm.

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Volkswagen AG CEO Martin Winterkorn announced today he is stepping down as the result of his company's cheating on emission tests, bypassing environmental standards and landing the company in regulatory hot water.

According to the U.S. Environmental Protection Agency, Volkswagen was able to cheat emissions tests for half a million of its U.S.-sold cars. The software that enabled cars to thwart emissions tests is in as many as 11 million other vehicles, Volkswagen admitted Tuesday.

Diesel cars from Volkswagen and Audi cheated on clean air rules by including software, likely a single line of code that made the vehicles' emissions look cleaner than they actually were.

The EPA described the software Volkswagen used as a "defeat device."

"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 EPA said in a statement.

So how was Volkswagen's exhaust system able to deceive emissions testing?

Arvind Thiruvengadam, a research assistant professor at West Virginia University, was  involved in a project last year that involved evaluating tailpipe emissions of diesel cars made by European manufacturers for the American market.

In an interview with Autoblog, Thiruvengadam told how his group drove a Volkswagen Jetta, a Passat and a BMW X5 for thousands of miles along California's highways to get their emissions results.

While the Passat should have been among the lowest in emissions of the three cars, tests showed 20 times the baseline level of emissions the team had established for the cars.

The research team reported its findings to the California Air Resources Board, which then further investigated. That ultimately led to the charges by the EPA.

Thiruvengadam said he hasn't researched the software that allowed Volkswagen to cheat on the tests. But he did say "there were lots of ways an electronic control unit could be programmed to identify testing and change its fuel mapping toward low emission in those rare scenarios."

For example, modern cars can sense when a hood is open for dynamometer testing, "so a smart hood switch could double as a defeat device."

Or, another sensor could detect when a vehicle's traction control unit was disabled, which is required during emissions testing, and place the emission system into a different mode.

"The possibilities are almost endless," he told Autoblog. "I'm pretty sure that if you're one of the largest car manufacturers, you could do a lot more."

So who authorized the algorithm?

Nikhil Kaul, a product manager at test/dev software maker SmartBear Software, said the code that enabled Volkswagen and Audi vehicles to detect when cars were being tested was likely extremely simple.

 

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