Diesel Particulate Filters act as a soot trap. In order to prevent the build up of soot deposits that will eventually block the filter and make changes to the running of the vehicle, they must be periodically cleaned out.
This is completed by active or passive regeneration.
Passive regeneration occurs on long continuous journeys where the exhaust temperature gets hot enough so that the soot deposits are consequently burnt off.
For vehicles that do not encounter this type of usage, active regeneration is required to burn off the soot deposits. Active regeneration occurs when the leve of soot deposits in the filter builds up to a maximum pre-determined leve.
At this point the vehicle’s ECU makes adjustments to the fuel injection and engine timing in order to increase the exhaust gas temperature.
This increases the temperatures within the DPF unit to a level where the accumulated soot deposits can be burned off. Some vehicles use a fuel additive to aid the regeneration process.
This fluid is added to the fuel tank each time the vehicle is filled with diesel.
Additives are often used on vehicles that do not have the space to locate the DPF closer to the engine where the temperatures will be at their highest.
The additive helps to lower the temperature at which the soot particules trapped in the DPF ignite and burn off, allowing regeneration to take place at a much lower temperature than it would otherwise take place at.