VIENNA: The European Court of Justice (CJEU) on Thursday ruled illegal software fitted to Volkswagen diesel vehicles which deactivates the filtering of polluting emissions at certain temperatures, paving the way for compensation for affected customers.

“Software in diesel vehicles which reduces the effectiveness of the emission control system at normal temperatures during most of the year constitutes a prohibited defeat device,” the EU’s court ruled.

The software reduces or even completely deactivates the filtering when temperatures are below 15 and higher than 33 degrees Celsius (59 degrees Fahrenheit).

“Emission limits laid down at EU level must be observed even where those temperatures are significantly below 15 degrees Celsius,” the court said in its rulings.

Austria’s Supreme Court and two regional courts brought the case to the CJEU following complaints of buyers, who bought Volkswagen vehicles between 2011 and 2013.