Modern vehicles remove most of the carbon through the Diesel Particulate Filter (DPF). The DPF has an internally designed filter element with wall fibres that attract fine soot particles. These particles are trapped in a filter element. In this process, a flammable liquid is electronically injected into the filter so that the stored particles can be burned and then expelled through the exhaust pipe.
When the Powertrain Control Module (PCM) detects that the DPF regeneration frequency does not match the data provided by the manufacturer, the diagnostic code P2459 OBDII will be set.