Cummins ISB6.7 CM2350 (2013-17) Fault Code: 4453 PID: SPN: 520669 FMI: 31 Aftertreatment Intermediate NH3 Sensor Closed Loop Operation – Condition Exists. The maximum dosing adjustment has been reached.

Cummins ISB6.7 CM2350 (2013-17) Fault Code: 4453 PID: SPN: 520669 FMI: 31 Aftertreatment Intermediate NH3 Sensor Closed Loop Operation – Condition Exists. The maximum dosing adjustment has been reached.

Circuit Description
The aftertreatment SCR intermediate NH3 (ammonia) sensor is a smart device that communicates with the engine control module via the J1939 data link. The aftertreatment intermediate NH3 sensor performs its own internal diagnostics and reports malfunctions back to the primary engine control module using the J1939 data link. The aftertreatment intermediate NH3 sensor is used to measure the ammonia in the aftertreatment system.

Component Location
The aftertreatment SCR intermediate NH3 sensor is located in the middle of the aftetreatment SCR catalyst.

Conditions for Running the Diagnostics
This diagnostic has to meet specific engine and aftertreatment conditions to run and complete. Sensor data is gathered over varying engine speeds and loads. When enough data has been gathered, the diagnostic will run, make a pass/fail decision, and begin to gather data again.

Conditions for Setting the Fault Codes
The Engine Control Module (ECM) detected the adjusted aftertreatment diesel exhaust fluid dosing command based on the aftertreatment SCR intermediate NH3 sensor has reached a maximum limit.

Action Taken When the Fault Code is Active
The ECM illuminates the amber CHECK ENGINE lamp and/or Malfunction Indicator Lamp (MIL) after the diagnostic fails on two consecutive trips.

Conditions for Clearing the Fault Code
It is necessary to use the “Reset All Faults” command in INSITE? electronic service tool to clear this fault and extinguish the amber CHECK ENGINE lamp and/or Malfunction Indicator Lamp (MIL).

Possible Causes:
Troubleshoot any aftertreatment intermediate NH3 sensor, aftertreatment diesel exhaust fluid dosing system, or any aftertreatment SCR temperature sensor fault codes prior to this fault code.