Mercedes-Benz OM 471 Introduction Into Service Manual page 143

System components
GF49.20>W>3007HA
ENGINES 471.9 in MODEL 963, 964 with CODE (M5Y) Engine version Euro V
ENGINES 471.9 in MODEL 963, 964 with CODE (M5R) Engine version EEV
Location
1 Exhaust aftertreatment unit
B73 Exhaust temperature sensor
downstream of SCR catalytic
converter
Task
The exhaust aftertreatment (ACM) control
unit (A60) registers the temperature of the
exhaust flow in the chamber downstream
of the SCR catalytic converter via the
exhaust temperature sensor downstream of
SCR catalytic converter (B73).
Design
The exhaust temperature sensor downstream of SCR catalytic
converter (B73) consists of a stainless steel housing. The inside
contains a measuring element, a PTC resistor. PTC stands for
"Positive Temperature Coefficient" and means that the electrical
resistance increases as the temperature increases.
140
Exhaust temperature sensor downstream of SCR catalytic converter, component
description
– This printout will not be recorded by the update service. Status: 09 / 2011 –
Function
The exhaust blowing by the sensor influences the measuring
element on the inside depending on its temperature and leads to
a change in its electric resistance.
Since a constant measurement current flows through the exhaust
temperature sensor downstream of SCR catalytic converter (B73),
there is a voltage drop due to the change in resistance, which the
exhaust aftertreatment (ACM) control unit (A60) can use to derive
the associated temperature value.
2.8.11
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