Audi's effort to emerge from the diesel scandal that has engulfed parent Volkswagen AG for more than a year suffered a setback as the luxury-car brand identified more cars in Europe that might breach emission rules.
This is the first time Audi has been accused of emissions manipulation by German authorities.
The affected models are said to pollute twice over the legal limit for nitrogen oxides (NOx) when the steering wheel is turned beyond 15 degrees.
A ministry spokesman said Volkswagen chief executive Matthias Mueller was summoned to the Berlin-based ministry on Thursday, without elaborating. Up till now Volkswagen has maintained that the emissions-control software found in its rigged EA189 diesel engine does not violate European law.
Germany's transport minister, Alexander Dobrindt has set a June 12 deadline for Audi to come up with a fix for the cars. The manufacturer agreed with German regulators on a recall that starts next month and affects 14,000 cars in its domestic market alone.
In March, German prosecutors searched several Audi offices suspicion of "fraud and illegal advertising", related to the cheating scandal.
A source close to Audi said problems in the interaction between transmission and engine control units are to blame for the emissions overshoot.