Nitrogen Oxide Sensor
The pre Selective Catalyst Reduction (SCR) NOx sensor is located in the exhaust pipe upstream of the SCR catalytic converter. The post SCR NOx sensor is located in the exhaust pipe downstream of the SCR catalytic converter. The NOx sensor comprises a sensor element attached to a dedicated NOx sensor module with a hardwired connection.
The NOx sensor and the NOx sensor module can be replaced as an assembly. The NOx sensor is an evolution of the wide band oxygen sensor. The NOx sensor is constructed from special ceramics. The NOx sensor contains 2 oxygen density detecting chambers that work together to determine the NOx concentration in the exhaust gas. The NOx sensor module sends messages to the Powertrain Control Module (PCM) via the Private Controller Area Network (CAN) bus. The PCM uses messages for monitoring the effectiveness of the SCR System.