A team of researchers from around the world have found the code buried deep in onboard software which enabled Volkswagen to circumvent American and European emissions tests for over six years before allegations of cheating surfaced in 2015.
The researchers, led by computer scientist Krill Levchenko from the University of California San Diego, obtained copies of Volkswagen onboard software from the company’s own maintenance website and from various forums online run by car enthusiasts, said the UC San Diego News Centre.
“We found evidence of the fraud right there in public view,” Levchenko said. “We found the system and how it was used.”
The code allowed the car’s onboard computer to determine the vehicle was undergoing an emissions test, and then activate emission-curbing systems to lower the pollutants emitted.
When a car is tested for emissions levels, it is placed on a chassis equipped with a dynamometer, which measures the engine’s power output. The test then begins a specific speed profile designed to imitate real-world urban driving with frequent stops.
Because the conditions for this test are standard across all stations, and publicly available, manufacturers are able to anticipate the exact conditions of the test. The code found in Volkswagen vehicles checks the speed, distance, and wheel position, and if it matches the conditions of the emissions test, the code will allow the onboard computer to activate the emissions-curbing system.
When the test was over, the onboard computer then deactivated these systems. Cars emitted up to 40 times the amount of nitrogen oxide allowed under US regulations once the emissions-curbing software was deactivated.
“The Volkswagen defeat device is arguably the most complex in automotive history,” Levchenko said.