The last rumoured explanation what they did was that they disable the emission control system when the AdBlue (carbamide) tank fill level drops under 10%. Accor

The last rumoured explanation what they did was that they disable the emission control system when the AdBlue (carbamide) tank fill level drops under 10%. According to the EU laws a diesel car isn't allowed to start if the AdBlue is empty so they didn't use it anymore, so it never gets empty...