Mitsubishi said that it would continue its own investigation into the matter and cooperate with German prosecutors in their probe.
Mitsubishi said the probe covered a 2.2-liter engine with the emissions standard Euro 5b, as well as 2.2-liter and 1.6-liter engines with the emissions standard Euro 6b.
Mitsubishi is the latest automaker to be investigated on suspicion of hiding illegal levels of pollution following a regulatory clampdown on emissions triggered by Volkswagen Group’s 2015 admission that it had cheated emissions tests.
German supplier Continental has said it is a cooperating witness in the probe.
Dutch authorities also ruled last week that diesel models made by Fiat Chrysler Automobiles and Suzuki broke European emissions rules and must be fixed or face a ban on sales across the region.