Catching Defeat Devices: How Systematic Vehicle Testing Can Determine the Presence of Suspicious Emissions Control Strategies

Despite regulatory limits, emissions of nitrogen oxide (NOₓ) from diesel vehicles are a major factor in air pollution. The authors estimate that each year in Europe about 6,800 deaths by excess NOₓ emissions could be avoided if diesel vehicles conformed to the limits set by emissions regulations. The Dieselgate scandal has raised awareness of defeat devices, which are software calibrations that turn off emission controls. In the United States, Dieselgate exposed one manufacturer, Volkswagen, using an illegal defeat device. In the European Union, the problem is much broader, because after Dieselgate it was apparent that most manufacturers in the EU were using defeat devices. The authorities in EU member states were not experienced in searching out defeat devices, and defeat devices illegal in the US were not illegal in the EU. There are some situations when it is appropriate to turn off emissions controls to protect the engine or the after-treatment system from damage, and regulations permit this. But in the EU the provision is used for unjustified deactivation of emissions controls. In the US, regulatory agencies have issued multiple guidelines and additional rules to define the boundary between proper and inappropriate deactivation of emissions controls. There is no such guidance in the EU, and EU regulators have tended not to question the claims of manufacturers. To help government agencies detect improper changes to calibration, this report describes a seven-step methodology for uncovering defeat devices during vehicle tests.


  • English

Media Info

  • Media Type: Digital/other
  • Edition: White Paper
  • Features: Appendices; Figures; References; Tables;
  • Pagination: 93p

Subject/Index Terms

Filing Info

  • Accession Number: 01716816
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Jul 9 2019 12:15PM