3.2.429. SPN 522392, FMI 31, SCR catalyst NOx sensors cross-connected

Description

The EEM monitoring system has detected that the NOx sensors are cross-connected.

Possible causes are:

  • The connectors are mixed between the NOx sensors.
  • The wiring is defective.
  • The NOx sensors are defective.

Reaction in EEM

The FC is stored and the warning lamp is activated. The CAN message indicates active fault.

NOTE: The present fault is classified as an emission related fault. Engine power will be reduced after a certain time which is defined by an authority.

Solution

First save the error log and then erase it. Restart the ECU after erasing the error log. If the fault occurs again during the next driving cycle, check the following paths:

  • Check the wiring of the NOx sensors. Use the Service tool to monitor the NOx sensor present state and disconnect one sensor. For example, if the upstream NOx sensor is disconnected, the user should see the “not present” in the downstream sensor state.
  • Check the NOx sensor wiring, the connectors and the contact surfaces of the connector pins (possible oxidation).
  • Check the operation with another NOx sensor to see if the NOx sensor is defective.

See NOx sensor for reference.