Types of Regeneration
There are 3 types of regeneration: passive, active, and forced.
This occurs during driving when the exhaust gas temperature is high enough, around 600°C, to burn off the soot as it passes through the filter.
Active regeneration is controlled by engine management and occurs when the soot load is greater than 45%. This usually happens when the vehicle is moving at more than 70 km/h at a constant speed for more than 10 minutes.
With active regeneration, the engine control unit injects more fuel into the engine to raise the exhaust gas temperature, thereby burning off soot from the particulate filter or DPF.
In order for active regeneration to take place, it is essential that more than a quarter of the fuel tank is filled. Otherwise the procedure will not be activated.
This is done using a diagnostic device, where the mechanic forces the vehicle to regenerate the filter. In most cases this operation can be performed with the vehicle stationary, however some models require road travel.