3.2.389. SPN 521023, FMI 31, Possible exhaust line NOx sensor interchangeΒΆ

Description

The exhaust line NOx sensors may be cross-connected.

Possible causes are:

  • The upstream and downstream NOx sensors are interchanged.
  • The upstream or downstream NOx sensor is 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 that the upstream and the downstream NOx sensors are connected correctly.
  • Check that the NOx sensors are not cross-connected.
  • Check the NOx sensor wiring, the connectors and the contact surfaces of the connector pins (possible oxidation).
  • Check that the both NOx sensors are effective. Change the defective sensor to a new one.

See NOx sensor for reference.