Germany this week ordered the recall of tens of thousands of cars produced by Volkswagen subsidiary Audi over "illegal software" designed to conceal levels of harmful emissions, the KBA vehicle licensing authority said on June 6.
"We have ordered that the illegal 'defeat devices' uncovered should be removed and the vehicles refitted according to the regulations," a KBA spokesman said.
"Defeat devices" refer to physical or software systems designed to reduce polluting emissions during regulatory tests, while allowing them to rise in real driving conditions.
Around 60,000 Audi A6 and A7 diesel cars in the European Union are affected by the recall, some 33,000 of them in Germany, the firm said.
In early May, Audi said it had stopped delivering some A6 and A7 versions to customers after finding "irregularities" in their onboard software, adding that it was working on a fix.
At the same time, the KBA said it was launching an inquiry into "suspicions of manipulation" in the cars.
News magazine Der Spiegel reported that the suspect software related to AdBlue, a fluid injected into the exhaust system to neutralize harmful nitrogen oxides (NOx).
The program reduced the amount of the liquid sprayed into the catalytic converter, aiming to lower consumption in between check-ups on the cars -- but allowing for higher emissions of the polluting gases.
German authorities warned Mercedes-Benz parent Daimler and Audi owner Volkswagen earlier this year that they could face mass recalls after similar AdBlue trickery was uncovered.
Meanwhile, prosecutors searched homes and offices belonging to Audi employees in Germany in February and in April.
Volkswagen's high-end subsidiary has long been in the focus of the "dieselgate" scandal, in which the Wolfsburg-based behemoth admitted in 2015 to installing software designed to dupe regulatory emissions tests in 11 million diesel-fuelled cars around the world.
Some vehicles' NOx emissions were up to 40 times higher than legal limits.
The scandal has already cost VW more than $25 billion (21 billion euros) in fines, compensation and buybacks, mainly in the United States.
Copyright Agence France-Presse, 2018
