5-49
• Continuous filter regeneration is impossible
under certain conditions such as low-speed driv-
ing. Under these conditions, the system auto-
matically raises the exhaust temperature to burn
the PM to regenerate the filter (automatic DPF
regeneration). However, even automatic DPF
regeneration is sometimes impossible if the
vehicle is repeatedly driven very slowly and the
engine is frequently started and stopped. The
DPF must then be regenerated by burning the
PM under manual control (parked DPF regener-
ation).
• The BlueTec
®
exhaust gas aftertreatment
reduces nitrogen oxides (NOx) by adding
(spraying) Diesel Exhaust Fluid (DEF) to an
area upstream of the selective catalytic reduc-
tion (SCR) catalyst using a device called the
DEF doser to decompose NOx into water and
nitrogen.
FE_FG.book Page 49 Monday, December 19, 2011 4:22 PM
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