The U.S. Environmental Protection Agency (EPA) and Cummins Inc. announced that Cummins will be voluntarily recalling roughly 500,000 model year 2010-2015 medium- and heavy-duty trucks. The recall will replace a faulty emissions control systems component that causes excess emissions of nitrogen oxides (NOx). This recall is the largest voluntary truck emissions recall to date. The problem Cummins is acting to correct is the result of a defective part and does not involve a defeat device, the EPA said.

The trucks being recalled are equipped with selective catalytic reduction (SCR) systems designed to control NOx emissions. NOx is a potent air pollutant that contributes to smog and fine particle formation in the atmosphere. The SCR catalysts that will be replaced through the recall were found to be less durable than is required, degrading within a few years instead of controlling NOx pollution for the regulatory full useful life of the vehicle. The recall will replace these SCR system components. The full useful life of medium-duty vehicles is 185,000 miles or ten years (whichever is first), and the full useful life of heavy-duty vehicles is 435,000 miles or ten years. The problem was discovered through government oversight programs that test vehicles for compliance with emissions standards throughout their useful life.