Selective Catalytic Reduction - Volvo 9700 Manual

Selective catalytic reduction

The bus is equipped with selective
catalytic reduction (SCR), used to reduce
emissions of nitrogen oxide and particles
in the exhaust gases.
The exhaust gases are cleaned using
the AdBlue urea solution, which is
injected into the exhaust system before
the SCR catalyst.
General
Heating
The cleaning process means that the
exhaust gases can become very hot.
Keep the area around hot components
clean. Be observant when using the
power take-off, for example, to ensure
that hot exhaust gases do not cause
damage.
Exhaust gases
The catalytic converter gets very hot and
cools more slowly than a normal
silencer. This means that the exhaust
gases retain their high temperature for a
longer period of time. A cloud of water
vapour may occur during cold starting.
This is more noticeable than for an
engine without exhaust gas cleaning.
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SCR System monitoring
AdBlue level
Should the AdBlue tank become empty,
immediately fill with AdBlue.
Driving without AdBlue means that there
is no exhaust gas after treatment, and
emissions from the engine increase. The
circulation of AdBlue is also used to cool
hot components.
Too low level of AdBlue also cause a
reduction in the engine's pulling power.
The next time the bus is at a standstill
with the engine running, for example at
traffic lights, the engine's pulling power is
reduced. The driver information display
will warn before performance reduction
occurs. The engine's pulling power
returns to normal as soon as it is refilled
with AdBlue.
NOTE
It may be a punishable offence to fail using
AdBlue or to try to interfere with the
exhaust cleaning system.
On-board diagnostic
There is a legal requirement that
necessitates a standardised approach to
monitoring the engine and the exhaust
gas cleaning. For this reason, the bus is
equipped with an on-board diagnostic
system (OBD) which monitors that the
exhaust gases fulfil the legal
requirement.
The OBD system monitors:
• The level of nitrogen oxides (NO
the exhaust gases.
• The level of particles (PM) in the
exhaust gases.
• AdBlue consumption, availability and
quality.
• Other functions in the engine and
exhaust gas cleaning system.
Symbol for fault in the exhaust gas cleaning
system
CAUTION
Always rectify faults as soon as possible.
Emission related faults
The symbol for malfunction indicator
lamp (MIL) illuminates in the event of
) in
x