It wasn't so long ago when Mitsubishi was near collapse. Then Carlos Ghosn, now former CEO of the Renault-Nissan alliance, bought a chunk of the struggling Japanese automaker in order to incorporate into that alliance. Mitsubishi's future finally seemed secure.

However, according to Reuters, German prosecutors are investigating Mitsubishi over suspected use of illegal defeat devices installed in its diesel engines. Although none of the company's US market vehicles, such as the Mitsubishi Outlander and Mitsubishi Eclipse Cross, are offered with diesel units, several other overseas-only vehicles are. The engines in question are the 1.6-liter and 2.2-liter four-cylinder diesels. Prosecutors also claim they are investigating an individual staff member of an international automaker for fraud, a unit of an international car dealership company, and two automaker suppliers.

Mitsubishi confirmed its German distributor and its European R&D facilities were the targets of the investigation. "No further information is available at that stage. Mitsubishi Motors will, of course, collaborate and contribute to this investigation," the company said. German auto supplier Continental is one of the two suppliers involved but the second currently remains unknown.

So-called defeat devices were unheard of until 2015 when Volkswagen admitted it rigged engine software with those devices in order to cheat US diesel emission tests. The German automaker immediately became the subject of multiple other investigations. It ultimately paid billions of dollars and euros in fines as part of settlement agreements. Customer vehicle buyback programs were also initiated.

Other automakers, such as Daimler and FCA, were also investigated for diesel emissions cheating and they too agreed to expensive settlements. At this stage, it's too early to know what will ultimately happen to Mitsubishi, but it certainly has a potentially serious problem. How this will affect Mitsubishi at a global level remains uncertain.