WASHINGTON — Ford Motor Co. is under criminal investigation by the U.S. Justice Department over its emissions certification practices, the auto giant disclosed Friday in a regulatory filing.

The inquiry is focused on Ford’s analytical modeling and resistance testing practices, the company said in its filing with the U.S. Securities and Exchange Commission. Ford said the investigation did not involve the use of defeat devices, the likes of which were used by Volkswagen to disguise emissions readings in millions of vehicles.

The German automaker paid nearly $15 billion to settle shareholder claims from the scandal and is now being sued by the SEC on charges of defrauding investors. In early April, European regulators accused Volkswagen, along with Daimler and BMW, of colluding to suppress emissions-fighting technology in violation of antitrust laws.

Fiat Chrysler, which used similar cheat devices in Jeep and Ram vehicles from 2014 to 2016, agreed to a $800 million penalty to resolve the case in January.

After employees raised concerns about the accuracy of emissions and gas mileage modeling methods in September 2018, Ford brought in an outside firm to review its emissions practices and hired an independent lab to conduct tests, the company announced in February.

“Ford also is evaluating potential changes to our road-load modeling process, including engineering, technical and governance components,” the company said in Friday’s statement.

It also voluntarily disclosed the matter to the Environmental Protection Agency and the California Air Resources Board, according to the SEC filing. The Dearborn, Michigan-based auto company said it has notified several other state and federal agencies, and that it is fully cooperating with authorities.

“Because this matter is still in the preliminary stages, we cannot predict the outcome, and we cannot provide assurance that it will not have a material adverse effect on us,” Ford said of the federal inquiry in the filing.

The Justice Department did not immediately respond to a request for comment from The Washington Post.

Ford posted better-than-expected earnings this week amid heightened demand for its trucks and SUVs in North America and cost-cutting in Europe. Net income for the first three months of the year fell 34 percent, to $1.15 billion, weighed down by charges totaling nearly $600 million. Adjusted profit came to 44 cents a share, blowing past analysts’ forecasts of 27 cents. Revenue fell to $40.34 billion from $41.96 billion a year earlier.