Federal transport authority KBA “filed charges” against Opel, accusing the manufacturer of “selling cars with manipulated exhaust control software,” senior prosecutor Nadja Niesen told AFP.
She added that across Europe, around 95,000 cars had fallen under suspicion. For its part, Opel acknowledged in a statement there were “preliminary proceedings on emissions” with searches at its factories in Ruesselsheim and Kaiserslautern.
It added that it was “fully cooperating with the authorities” and “reaffirms that its vehicles comply with the applicable regulations”.
Tracing its roots back more than 150 years, Opel and British subsidiary Vauxhall were bought last year by Peugeot maker PSA after decades under US-based General Motors.
It was until recently one of a few corners of the mighty German auto industry relatively untouched by “dieselgate”.
The scandal followed Volkswagen's 2015 admission to fitting 11 million cars worldwide with software — so-called “defeat devices” — to make cars appear less polluting in lab tests than in real on-road driving.
The transport ministry in Berlin announced in July that it would question Opel relating to three models meeting the latest “Euro 6” emissions standards.
In a statement Monday, ministry officials said they would soon issue an official recall for the models — the Cascada, Insignia and Zafira — which it discovered were fitted with a defeat device.
Opel had managed to “constantly delay the recall hearing with technical arguments,” they added.
The ministry further said that Opel had been slow to carry out software updates it ordered to fix four defeat devices found in older vehicles at the end of 2015.
In grip of 'dieselgate'
Household names of the German car industry like BMW or Mercedes-Benz parent Daimler have long since become the targets of official probes relating to the ever-widening “dieselgate” scandal that began with VW.
In Europe, car firms have escaped the swingeing costs for fines, buybacks and compensation — 27 billion euros so far — that the Wolfsburg-based group has paid out in the United States.
But managers and executives at the sprawling 12-brand Volkswagen empire — up to and including former chief executive Martin Winterkorn — have been targeted with court cases for withholding information from investors, fraud and false advertising over the emissions affair.
At subsidiary Audi, former chief executive Rupert Stadler recently quit his post after months spent in custody, which prosecutors said was necessary to stop him influencing witnesses.
And the industry is fighting a rearguard action against tougher European regulations on harmful nitrogen oxides (NOx) and other emissions from diesel vehicles, as well as outright bans for older models from some German city centres.