After testing 53 models of passenger vehicles meeting Euro 5 and 6 emissions requirements for diesel engines, the German federal motor transport authority (Kraftfahrt-Bundesamt) found that laboratory testing and real-world testing yield significantly differing results in emissions. The report has resultedin 630,000 vehicles being voluntarily recalled by manufacturers to change emissions controls.
Specifically, the report found that diesel engines utilizing a thermofenster (thermal window) technique to limit emissions controls during engine operations at low temperatures, legally allowed as a means of protecting the engines, may be too aggressive. This results in the engines bypassing the emissions controls too often, resulting in higher emissions – especially of NOx gasses. The German transport minister has asked for a further restriction of that thermal window and most manufacturers are complying voluntarily, issuing the recall to change systems on affected vehicles.
