Ford Motor Co. said Friday that the Justice Department has opened a criminal investigation into its U.S. emissions certification process.
The automaker said in a regulatory filing that the "matter currently focuses on issues relating to road load estimations, including analytical modeling and coastdown testing."
In September, a group of employees reported possible problems with a mathematical model used to calculate pollution and mileage, prompting Ford to hire an outside firm to run tests. And in February, Ford launched an investigation into whether it overstated gas mileage and understated emissions from a wide range of vehicles.
Ford voluntarily disclosed the matter to the U.S. Environmental Protection Agency and the California Air Resources Board in February. It has also notified a number of other state and federal agencies.
Ford said Friday it's fully cooperating with all government agencies.
The investigation makes Ford at least the third major automaker to be the focus of U.S. scrutiny over emissions in the span of a few years. Volkswagen paid a $4.3-billion penalty in 2017 for misleading regulators and customers about its diesel engines’ emissions. Fiat Chrysler Automobiles, which last month recalled almost 863,000 vehicles that violate pollution standards, faces a criminal investigation, Bloomberg News has reported.