The highly efficient oxidation catalytic converter is positioned upstream of a diesel particulate filter. The catalyst oxidizes hydrocarbons, carbon monoxide and nitrogen monoxide to nitrogen dioxide. The soot deposits on the diesel particulate filter are continuously burnt off by the nitrogen dioxide that has been produced previously on the catalyst. The excess nitrogen dioxide required can be limited by appropriate adjustment of the catalytic converter. The engine's nitrogen oxide emissions are reduced slightly.

The modular CRT^® system does not require regeneration aids. It is reliable and low-maintenance.

To ensure that the modular CRT^® system works optimally, the following basic conditions must be fulfilled:

• Sulphur-free fuel with max. 50 ppm S (0.005 % sulphur content)
• Suitable use profile, i.e. a temperature window of 250 - 450 °C at the filter position
• The engine must have been serviced in compliance with the manufacturer's recommendations.