In its complaint on Tuesday, the Justice Department noted that the engine controls in the Ram trucks and Jeeps are different from what are described in paperwork the company filed with the E.P.A.

The features of the software, it said, “alone or in combination with one or more of the others, bypass, defeat and/or render inoperative” the vehicles’ emission control system, causing them to emit “emit substantially higher levels” of nitric oxide than allowed.

The E.P.A. made its accusation after Volkswagen’s admission that it had used “defeat device” software to enable its cars to pass emissions tests while spewing far more pollutants than allowed in normal driving.

Volkswagen, of Germany, ended up paying billions of dollars in fines, several of its executives have been investigated or charged with crimes. As part of a settlement with authorities in the United States, Volkswagen is buying back hundreds of thousands of diesel cars from American customers.

United States officials view the Fiat Chrysler matter as less serious, and stopped short of accusing the company of intentionally engineering the software to cheat on emissions tests. Filing the suit is seen as an effort to accelerate settlement negotiations, after the company outlined its proposal last Friday to reset the engine software in the affected vehicles.