German carmaker Daimler said it is conducting an internal investigation into emissions of its vehicles.
The parent company of Mercedes-Benz said the move came after the Justice Department asked it earlier this month to review its "certification and admissions process related to exhaust emissions in the U.S."
The automaker said Thursday that it was asked to keep the matter confidential and that it agreed to fully cooperate with U.S. authorities.
A group of Mercedes-Benz customers in the U.S. filed a class-action lawsuit in February, claiming that some diesel vehicles are emitting above legal levels in low temperatures, and are programmed not to yield those results in emission tests.
"Daimler will consequently investigate possible indications of irregularities and of course take all necessary actions," the company said in a statement.
The announcement comes on the same day as another German carmaker Volkswagen’s settlement in its emission scandal with U.S. authorities was approved by an American judge.
In that deal, the company offered 580,000 owners of its diesel vehicles on U.S. roads the option to buyback vehicles or fix them to meet U.S. emission standards.
By Ovunc Kutlu in New York