DPF Regeneration

Passive regeneration happens on its own during steady, fast driving, when the exhaust is hot enough. Active regeneration is started by the control unit, which raises the exhaust temperature with extra post-injection. An active regeneration takes from a few minutes to around twenty minutes. You may notice a higher idle, the cooling fan running, a hot smell or a slight rise in fuel consumption.

Passive regeneration happens on its own during long, fast journeys when exhaust is hot enough. Active regeneration is triggered by the control unit with extra fuel injection.

The control unit decides when to regenerate from the soot model and the differential pressure reading. It needs the engine warm and the car driven steadily to complete. Some systems also use a fuel additive stored in a separate tank to lower the temperature at which soot burns.

Interrupting regenerations repeatedly, typically with short trips, leads to a blocked filter. If the DPF light comes on, the manual usually recommends a sustained drive at moderate speed; if that does not help, a workshop can start a forced regeneration. Repeatedly interrupting regenerations can lead to a blocked filter and oil dilution. If the DPF light comes on, a drive of about 20 minutes at a steady speed often allows regeneration to finish, if your manual recommends it.