When in September 2015 environmental activist and scientists revealed that Volkswagen had installed a software in his diesel cars that fraudulently manipulated the exhaust gas values, an uproar went through the car industry. But the real big question was: Who else made use of such illegal tricks? The answer is that many did, but some succeeded in avoiding the appearance of fraud, using tricks of doubtful character anyway – things like an “engine temperature window” that switches off the exhaust gas treatment at low ambient temperatures – in one case even at ambient temperatures as high as 18°C. In many other cases, environmentalists simply were unable to provide a prove that such a defeat device exists; they failed due to the black box character of the engine control software running in the cars.
Now a team of scientists from the Ruhr University (RUB, Bochum, Germany) and the University of California, San Diego, along with the independent IT expert Felix Domke have developed a software tool that allows them to analyze the embedded engine control software in detail. The team tested 900 different versions of the engine control software for diesel vehicles from Volkswagen and Fiat Chrysler from the past eight years. In 400 of them they found a device that switched off exhaust gas cleaning under regular driving conditions; under test stand conditions, the cleaning process was activated. The analysis also reveals how exactly the manufacturers were doing in the fraud.
The standard exhaust gas test on a test stand takes about 20 minutes. The tool developed by the scientists does not take that long; actually, it does not even need a car – instead of measuring exhaust gases, it analyses the software running in the engine control unit. In about two minutes of testing, the tool can detect whether or not the ECU contains a shutdown device. On the basis of the software, the researchers can understand how a car reacts to certain conditions, for example, which exhaust gas filter mechanisms are activated in a particular situation.