During normal operation, soot accumulates in the Diesel Particulate Filter (DPF). The soot load is continuously calculated based on fuel consumption, differential pressure across the filter, and operating hours. When the soot load reaches a certain level, the E-ECU (Engine Electronic Control Unit) decides that regeneration is needed. The regeneration process begins with diagnostic functions checks and then moves on to the Diesel Oxidation Catalyst (DOC) light-off state.
Passive regeneration occurs continuously if the exhaust temperature is between 280-350°C (536–662°F). The amount of burned soot depends on the engine load. During passive regeneration, there is no light-off in the DOC.
When the soot load exceeds a predetermined level, the Control Unit requests the start of regeneration. If accepted by the operator, late post-injection is activated in the cylinder. Extra fuel is injected into the cylinder, mixed with the exhaust gas, and transferred to the DOC. In the DOC, a light-off occurs if the engine speed is above 1200 rpm and the exhaust temperature before the DOC is above 220~280°C
Once the DOC light-off is reached, the exhaust temperature is raised to 550-650°C . The regeneration process remains active for 30 minutes. If the engine speed or exhaust temperature decreases below the specified values, regeneration will be temporarily aborted. Ignoring or aborting the regeneration request will result in engine performance derating.
If the regeneration request is ignored or aborted twice, a derate will occur, and the machine will require a standstill regeneration. During standstill regeneration, the E-ECU takes control of the engine and sets it to certain loads and engine speeds. If regeneration continues to be ignored or aborted, it is not possible to start regeneration from the machine. VCADS Pro must be used to initiate regeneration safely, as there is a risk of uncontrolled soot fire. If regeneration is ignored for a fourth time, it is not possible to regenerate at all, and the DPF must be replaced.