CarScan

Diesel particulate filter

The diesel particulate filter: the differential pressure sensor, regeneration and soot overload. Half the codes in this group are not about hardware but about the driving pattern: the filter cleans itself, but only with a warm exhaust and at speed.

6 codes in this section, 6 with a guide

What it usually turns out to be

  • Regeneration never finishes — most often because the trips are short: an hour on the motorway does more than replacing parts.
  • Regeneration running too often means more soot than normal is being made: look for the cause in the engine, not in the filter.
  • A pinched or cracked pressure pipe produces the same codes as a dead sensor.