Mercedes-Benz OM 471 Introduction Into Service Manual page 158

GF09.41>W>4125H
ENGINES 471.9 in MODEL 963
Location
B617 Charge temperature sensor in
charge air housing
The charge air temperature sensor in the
charge air housing (B617) is located on the
charge air housing.
Task
Over the charge air temperature sensor downstream in the charge
air housing (B617), the engine management (MCM) control unit
(A4) detects the temperature of the charge air shortly before it
enters the combustion chamber.
The engine management (MCM) control unit (A4) determines the
effective recycled exhaust mass using the charge air temperature
and values from the exhaust recirculation (AGR) differential
pressure sensor (B621) which plays a significant role in calculating
the exhaust recirculation rate.
Design
There is an NTC resistor located inside the charge air temperature
sensor in the charge air housing (B617). NTC stands for "Negative
Temperature Coefficient", which means that electrical resistance
falls as temperature rises.
i Introduction of engine OM 471 and exhaust aftertreatment > 09/2011 >
Component description for charge temperature sensor in charge air housing
– This printout will not be recorded by the update service. Status: 09 / 2011 –
System components
Function
The charge air prevailing at the charge air temperature sensor in
the charge air housing (B617), depending on its temperature,
influences the temperature of the measuring element inside the
sensor and thus the magnitude of the electrical resistance. The
engine management (MCM) control unit (A4) deduces the
associated temperature from the electrical resistance.
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