About 3.6 million diesel cars equipped with 1.6 litre engines manufactured by Volkswagen will require hardware changes to remove emission-cheating technology, Germany’s Ministry of Transportation said on Friday.
The announcement has come one day after the testimony from Volkswagen’s US chief Michael Horn in front of the Energy and Commerce Committee of the US Congress.
During the testimony, Horn said the installation of emission-cheating software in Volkswagen’s EA 189 diesel engines was a decision made by a small group of engineers and not the firm’s top officials.
"To my understanding, this was not a corporate decision; this was something individuals did," Horn said.
"I agree it's very hard to believe and I personally find it hard to believe," he added.
The US Environmental Protection Agency, which revealed the existence of the so-called defeat device to the public last month, has requested that the car-maker provide details of how it intends to fix the engines next week.
In the US, almost half a million cars, mostly Volkswagen’s flagship Passat vehicles, will have to be recalled.
Overall, 11 million vehicles manufactured by the Volkswagen Group have been sold around the world, eight million of those in Europe. Cars of other brands of the Volkswagen family including Audi, Skoda and Seat have also been affected.
2.0 litre engines can be corrected with a simple software fix, while 1.6 litre engines will require hardware changes, Volkswagen admitted.
In the US, the software fix will have to be approved by the EPA as well as the California Air Resources Board before implementation.
"EPA and CARB will immediately begin evaluating the proposed software," the EPA said.
Volkswagen said the affected cars fall into three generations of vehicles. The most recent models, known as Generation 3, number around 70,000 and would be the first to receive a fix.
EPA described the 2012-2014 Passats as Generation 2 vehicles, which Volkswagen said number around 90,000. Horn told lawmakers that Generation 2 vehicles could begin to receive fixes around the middle of next year.
The oldest cars, 325,000 vehicles grouped as Generation 1, would require major changes including the installation of new hardware. No date has been set for those vehicles to begin receiving remedies.
On Thursday, German newspaper Sueddeutsche Zeitung reported that Volkswagen's manipulation software was also switched on during European emission tests, citing a company spokesman.