Mercedes-Benz OM 471 Introduction Into Service Manual page 139

System components
GF49.20>W>3004H
ENGINES 471.9 in MODEL 963, 964 with CODE (M5Z) Engine version Euro VI
Location
1 Exhaust aftertreatment unit:
B68 Exhaust temperature sensor
downstream of upper diesel
oxidation catalytic converter
Task
The exhaust aftertreatment control unit
(ACM) (A60) records the temperature of the
exhaust flow downstream of the upper
diesel oxidation catalytic converter (DOC)
via the exhaust temperature sensor
upstream of the upper diesel oxidation
catalytic converter (B68).
Design
The sensor consists of a stainless steel housing. The housing
contains a measuring element, a PTC resistor.PTC stands for
"Positive Temperature Coefficient" and means that the electrical
resistance increases as the temperature increases.
136
Exhaust temperature sensor downstream of upper diesel oxidation catalytic
converter, component description
– This printout will not be recorded by the update service. Status: 09 / 2011 –
Function
Depending on its temperature, the gas flowing past the probe
influences the measuring element inside, and makes its electrical
resistance change.
Since the sensor has a constant measuring current flowing
through it, the resistance change causes a voltage drop, via which
the exhaust aftertreatment control unit (ACM) (A60) can work out
the associated temperature value.
20.7.11
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