Nox jednostavno nastaje u uslovima visoke temperature sagorevanja efikasnih td motora, jedini lek za tretman je adblue koji vw nije imao u to vreme:
"To deal with this problem, in 2005 Volkswagen licensed Mercedes' urea-based selective catalytic reduction (SCR) system called BlueTec for future diesel engine development. While effective at reducing NOx, an SCR system like Bluetec was expensive, high-maintenance and required more space than other methods, making it unsuitable for Volkswagen's compact cars such as Golf or Jetta. Some managers at Volkswagen rejected BlueTec, and preferred to develop their own inexpensive "lean NOx trap" system. In 2007, Volkswagen canceled the licensing deal for BlueTec and announced that it would use its own pollution control technology.
Volkswagen chose the "lean NOx trap" system for its turbo-diesel Golf and Jetta models, but the solution did not work well as it required a fuel-rich exhaust gas in the purification process and fuel economy suffered as a result. Nonetheless, the company promoted the technological miracle of fast, cheap, and green diesel vehicles – but the impression projected to outsiders did not reflect the reality. In reality, the system failed to combine lower fuel consumption with compliant NOx emissions, and Volkswagen chose around 2006 to program the Engine Control Unit (ECU) to switch from lower fuel consumption and high NOx emissions to low-emission compliant mode when it detected an emissions test, particularly for the EA 189 engine. This caused the engine to emit NOx levels above limits in daily operation, but comply with US NOx standards when being tested, constituting a defeat device."
