German carmaker, Volkswagen has announced plans to refit up to 11 million vehicles containing the rigged software as the company is under huge pressure to address the worst business crisis in its 78-year history, on Tuesday.
New Chief Executive Matthias Mueller said the German carmaker would ask customers "in the next few days" to have diesel vehicles that contained illegal software refitted, a move which some analysts have said could cost more than $6.5 billion.
Volkswagen has said previously about 11 million vehicles were fitted with software capable of cheating emissions tests.
"We are facing a long trudge and a lot of hard work," Mueller told a closed-door gathering of about 1,000 top managers at Volkswagen's Wolfsburg headquarters late on Monday.
"We will only be able to make progress in steps and there will be setbacks," he said, according to a text seen by Reuters.
Volkswagen did not say how the planned refit would make cars with the "cheat" software comply with regulations, or how this might affect vehicles' mileage or efficiency, which are important considerations for customers.
VW admitted a week ago that emissions tests it was conducting on its diesel vehicles sold in the United States were manipulated, after the practice was uncovered by US environmental authorities.
The software senses when the car has been set up for emissions testing and then produces much lower levels of nitrogen oxides in the exhaust emissions than it would give off during normal road use.
Mueller was appointed CEO on Friday to replace Martin Winterkorn. German prosecutors said on Monday they were investigating Winterkorn over allegations of fraud.
Additional reporting from Reuters
