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EPA Cracks Down on Diesel Engine Defeat Devices

Road Rail Air Water

A defeat device is any motor vehicle hardware, software, or design that interferes with or disables emissions controls under real-world driving conditions, even if the vehicle passes formal emissions testing. The term appears in the Clean Air Act regulations (Section 203(a)(3)(b)), to describe anything that prevents an emissions control system from working. Defeat devices are more commonly used than most people realize, and EPA is cracking down on companies that sell, install, or use this illegal equipment.

Tampering of engines to bypass manufacturer emissions controls, results in significantly higher releases of nitrogen oxides and particulate matter, both of which contribute to serious public health problems in the US. These problems include premature mortality, aggravation of respiratory and cardiovascular disease, aggravation of existing asthma, acute respiratory symptoms, chronic bronchitis, and decreased lung function. Numerous studies also link diesel exhaust to increased incidence of lung cancer. Further, emission controls tampering impedes federal, state, and local efforts to implement air quality standards that protect public health.

Many of the companies caught and fined by EPA are in areas having high levels of air pollution, including higher than average levels of diesel particulate matter, and socioeconomic burdens. EPA is strengthening enforcement in such communities to address disproportionately high effects of pollution on vulnerable populations.

EPA has taken numerous enforcement actions against vehicle makers and other companies that have used or installed defeat devices, whether deliberately, or through error or negligence.  These illegalities, which date back to the 1970's (and don't forget Volkswagen's DieselGate), unfortunately continue today, but EPA is fighting back. Beginning in 2020, EPA established a National Enforcement Compliance Initiative (NECI) that focuses on stopping the manufacture, sale, and installation of defeat devices on vehicles and engines used on public roads as well as on nonroad vehicles and engines. Those efforts are paying big dividends. Below are headlines from a six month period in 2023:

To assist with enforcement, EPA has provided tampering and aftermarket defeat device inspector trainings attended by 26 states and the District of Columbia since the inception of the NECI.

EPA also supported states performing inspections and taking enforcement actions for violations of state laws concerning tampering. States' efforts to curtail the demand for aftermarket defeat devices complement the EPA's efforts, which are generally focused on the manufacturing and supply of aftermarket defeat devices.