Regeneration
Soot from diesel combustion continuously accumulates in the closed
diesel particulate filter. To guarantee longer filter change intervals and
a long filter service life, regular regeneration of the diesel particulate
filter is necessary.
High exhaust temperatures effectively reduce the soot. As the exhaust
gas temperatures are not always sufficient to produce continual soot
reduction (passive regeneration), there is an automatic triggering of
active regeneration, which is dependent on the operational profile
of the vehicle. If necessary, the driver will be requested to initiate the
regeneration manually when the vehicle is stationary. To do this the
idling speed is increased to approx. 1400 rpm in order to achieve
the optimum exhaust gas temperature.
The percentage of passive or active regeneration is dependent on the
engine load and the vehicle’s usage profile.
Passive regeneration
• Continuous, at exhaust gas temperatures > 250°C
• No additional diesel injection into exhaust flow
• Takes place during driving without the driver noticing
Active regeneration
• Takes place subject to conditions of vehicle operation
• Triggered automatically with notification in instrument cluster,
no action required from driver
• Additional diesel injection to increase the exhaust temperature
• Can be suppressed by means of theInhibit switch in dangerous
situations or special operations
• Regeneration can be effected manually with vehicle at a standstill
when notification appears in instrument cluster
DPF regeneration
switch
Information field
“Regeneration
deactivated”
Information field
“Regeneration
overdue”
i
Information fields on the display show
when the Inhibit switch is active and
indicate when regeneration is overdue.
1
Inhibit function (block/allow regeneration)
2
Initiate regeneration manually
Special operations/emergencies
The Inhibit function serves solely to suppress the regenera-
tion process briefly in exceptional situations and must
be reset manually after use. Permanent use of the Inhibit
function will lead to premature filter loading which cannot
be reduced. Unscheduled replacement of the filter will
then be necessary.
1
2
Engine
Technical Manual
24
Mercedes-Benz Special Trucks