DEARBORN, Mich. — Ford Motor Co. revealed it is the subject of a U.S. Department of Justice investigation into the factory’s emissions testing and certification processes in a report filed with the U.S. Securities and Exchange Commission.

In February, Ford’s directors self-reported to the EPA their concerns that engineers may have failed to properly calculate the effects of drag and tire friction in laboratory testing. At the time, executives said they could not be sure whether fuel economy ratings or emissions certifications would be affected. An outside law firm, Sidley Austin, was hired to investigate the matter and presumably oversee retesting.

“Our focus is on completing our investigation and a thorough technical review of this matter and cooperating with government and regulatory agencies,” said Kim Pittel, Ford’s vice president of sustainability, environment, and safety engineering, in a statement.

Ford is only the latest vehicle manufacturer to face scrutiny over emissions testing. In 2014, Hyundai and Kia paid a $100 million penalty for inflating the fuel economy ratings of more than 1 million units sold in the U.S. In 2017, the “Dieselgate” scandal cost Volkswagen billions of dollars in penalties and awards, including dealer compensation. More recently, Fiat Chrysler agreed to a multimillion-dollar settlement to resolve claims brought by the DOJ and the California Air Resources Board.

To read Ford’s SEC filing, click here.