Location
1 | Exhaust aftertreatment unit |
B67 | Exhaust temperature sensor upstream of diesel oxidation catalytic converter |
W49.20-A001-76
Task
The exhaust gas aftertreatment (ACM) (A60a) control unit records the temperature of the exhaust flow in the entry chamber of the exhaust gas aftertreatment unit (1) via the temperature sensor exhaust gas before diesel oxidation catalytic converter (B67).
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 flowing by the sensor affects the measuring element in its interior depending on the temperature. To be more precise, its electrical resistance changes. For this change in resistance to be a measurable electrical initial parameter, a constant measurement current flows through the sensor. The voltage drop involved allows the exhaust gas aftertreatment (ACM) control unit (A60a) to infer the resistance value first and thus the associated temperature value.