Location
1 | Exhaust aftertreatment unit |
B67 | Exhaust temperature sensor upstream of diesel oxidation catalytic converter |
W49.20-1078-76
Task
Via the exhaust temperature sensor upstream of the diesel oxidation catalytic converter (B67) the exhaust aftertreatment (ACM) control unit (A60) records the temperature of the exhaust flow in the deflection chamber upstream of the diesel oxidation catalytic converter (DOC).
Structure
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.
Function
The exhaust gas 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 the sensor has a constant measuring current flowing through it, the resistance change causes a voltage drop, via which the exhaust aftertreatment (ACM) control unit (A60) can work out the associated temperature value.