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Reason:
Aftertreatment Diesel Exhaust Fluid Pressure Sensor – Data Valid But Above Normal Operating Range – Moderately Severe Level. The diesel exhaust fluid dosing unit has detected a blockage in the diesel exhaust fluid return flow.

Effect:
Possible reduced engine performance

Circuit Description:
The Engine Control Module (ECM) provides a 5 volt supply and a ground to the aftertreatment diesel exhaust fluid pressure sensor. The pressure sensor provides a signal to the ECM on the sensor signal circuit. This sensor signal voltage changes, based on the aftertreatment diesel exhaust fluid pressure supplied by the dosing unit. The ECM will detect a low signal voltage at low diesel exhaust fluid pressures, and a high signal voltage at high diesel exhaust fluid pressures.

Component Location:
The aftertreatment diesel exhaust fluid pressure sensor is internal to the aftertreatment diesel exhaust fluid dosing unit and can not be serviced separately.

Conditions for Running the Diagnostics:
This diagnostic runs continuously when the keyswitch is in the ON position or when the engine is running.

Conditions for Setting the Fault Codes:
The Engine Control Module (ECM) detected the aftertreatment diesel exhaust fluid pressure was greater than 1100 kpa [159 psi] for more than 20 seconds.

Action Taken When the Fault Code is Active:
1) The ECM illuminates the amber CHECK ENGINE lamp and/or Malfunction Indicator Lamp (MIL) after the diagnostic fails on two consecutive trips.
2) Engine torque will be reduced if the engine is operated for an extended period of time with this fault active.
3) Engine torque will be severely reduced.
4) Vehicle speed will be limited to 8 km [5 mi] per hour after extended engine operation with the fault code active.

Conditions for Clearing the Fault Code:
1) To validate the repair, perform the “Aftertreatment Diesel Exhaust Fluid Doser Pump Override Test” found under “ECM Diagnostic Tests” in the INSITE™ electronic service tool
2) The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.
3) The ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.
4) For On-Board Diagnostics (OBD) engines, the ECM will extinguish the Malfunction Indicator Lamp (MIL) after three consecutive trips where the diagnostic runs and passes.
5) The Reset All Faults command in INSITE™ electronic service tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.

Shop Talk:
Reference the appropriate OEM wiring diagram when troubleshooting circuits that utilize wiring supplied by the OEM.

For intermittent power supply and datalink communication issues with Aftertreatment Components, it is highly recommended that the OEM Power Distribution Center fuses and relays be thoroughly checked for loose, missing or intermittent connections.

Troubleshoot other active SCR related faults before this fault.

Possible Causes:
1) Blocked, restricted, or frozen diesel exhaust fluid dosing unit return line or return line fitting
2) Malfunctioning diesel exhaust fluid dosing unit

Reason:
Aftertreatment Diesel Exhaust Fluid Pressure Sensor – Data Valid But Above Normal Operating Range – Moderately Severe Level. The diesel exhaust fluid dosing unit has detected a blockage in the diesel exhaust fluid return flow.

Effect:
Possible reduced engine performance

Circuit Description:
The Engine Control Module (ECM) provides a 5 volt supply and a ground to the aftertreatment diesel exhaust fluid pressure sensor. The pressure sensor provides a signal to the ECM on the sensor signal circuit. This sensor signal voltage changes, based on the aftertreatment diesel exhaust fluid pressure supplied by the dosing unit. The ECM will detect a low signal voltage at low diesel exhaust fluid pressures, and a high signal voltage at high diesel exhaust fluid pressures.

Component Location:
The aftertreatment diesel exhaust fluid pressure sensor is internal to the aftertreatment diesel exhaust fluid dosing unit and can not be serviced separately.

Conditions for Running the Diagnostics:
This diagnostic runs continuously when the keyswitch is in the ON position or when the engine is running.

Conditions for Setting the Fault Codes:
The Engine Control Module (ECM) detected the aftertreatment diesel exhaust fluid pressure was greater than 1100 kpa [159 psi] for more than 20 seconds.

Action Taken When the Fault Code is Active:
1) The ECM illuminates the amber CHECK ENGINE lamp and/or Malfunction Indicator Lamp (MIL) after the diagnostic fails on two consecutive trips.
2) Engine torque will be reduced if the engine is operated for an extended period of time with this fault active.
3) Engine torque will be severely reduced.
4) Vehicle speed will be limited to 8 km [5 mi] per hour after extended engine operation with the fault code active.

Conditions for Clearing the Fault Code:
1) To validate the repair, perform the “Aftertreatment Diesel Exhaust Fluid Doser Pump Override Test” found under “ECM Diagnostic Tests” in the INSITE™ electronic service tool
2) The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.
3) The ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.
4) For On-Board Diagnostics (OBD) engines, the ECM will extinguish the Malfunction Indicator Lamp (MIL) after three consecutive trips where the diagnostic runs and passes.
5) The Reset All Faults command in INSITE™ electronic service tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.

Shop Talk:
Reference the appropriate OEM wiring diagram when troubleshooting circuits that utilize wiring supplied by the OEM.

For intermittent power supply and datalink communication issues with Aftertreatment Components, it is highly recommended that the OEM Power Distribution Center fuses and relays be thoroughly checked for loose, missing or intermittent connections.

Troubleshoot other active SCR related faults before this fault.

Possible Causes:
1) Blocked, restricted, or frozen diesel exhaust fluid dosing unit return line or return line fitting
2) Malfunctioning diesel exhaust fluid dosing unit

Reason:
Aftertreatment Diesel Exhaust Fluid Return Valve – Voltage Above Normal or Shorted to High Source. High signal voltage detected at the aftertreatment diesel exhaust fluid return valve.

Effect:
Possible reduced engine performance

Circuit Description:
The aftertreatment diesel exhaust fluid return valve is controlled by the Engine Control Module (ECM). The return valve position determines where diesel exhaust fluid will flow as it exits the dosing unit. When the return valve is activated, the dosing system will purge and return the diesel exhaust fluid in the lines to the tank.

Component Location:
The aftertreatment diesel exhaust fluid return valve is internal to the aftertreatment diesel exhaust fluid dosing unit and can not be serviced separately.

Conditions for Running the Diagnostics:
This diagnostic runs continuously when the keyswitch is in the ON position or when the engine is running.

Conditions for Setting the Fault Codes:
The Engine Control Module (ECM) detected the aftertreatment diesel exhaust fluid return valve circuit was out of range high or open.

Action Taken When the Fault Code is Active:
1) The ECM illuminates the amber CHECK ENGINE lamp and/or the Malfunction Indicator Lamp (MIL) immediately when the diagnostic runs and fails.
2) Diesel exhaust fluid injection into the aftertreatment system is disabled.
3) Engine torque will be reduced if the engine is operated for an extended period of time with this fault active.

Conditions for Clearing the Fault Code:
1) To validate the repair, perform a key cycle, start the engine and let it idle for 1 minute.
2) The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.
3) The ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.
4) For On-Board Diagnostics (OBD) engines, the ECM will extinguish the Malfunction Indicator Lamp (MIL) after three consecutive trips where the diagnostic runs and passes.
5) The Reset All Faults command in INSITE™ electronic service tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.

Shop Talk:
If this fault is active, the dosing system may not be able to purge, which means there will be aftertreatment diesel exhaust fluid left in the lines. Care must be taken when removing connections. Also, lines can freeze and the SCR system can become damaged in cold weather if the system is not properly purged.

Reference the appropriate OEM wiring diagram when troubleshooting circuits that utilize wiring supplied by the OEM.

For intermittent power supply and datalink communication issues with Aftertreatment Components, it is highly recommended that the OEM Power Distribution Center fuses and relays be thoroughly checked for loose, missing or intermittent connections.

Possible Causes:
1) Inactive fault codes
2) Damaged aftertreatment DEF return valve and electrical connections
3) Faulty ECM
4) Faulty OEM harness
5) Open circuit
6) Pin-to-pin short circuit

Reason:
Aftertreatment Diesel Exhaust Fluid Return Valve – Voltage Below Normal, or Shorted to Low Source. Low signal voltage detected at the diesel exhaust fluid return valve.

Effect:
Possible reduced engine performance.

Circuit Description:
The aftertreatment diesel exhaust fluid return valve is controlled by the Engine Control Module (ECM). The return valve position determines where diesel exhaust fluid will flow as it exits the dosing unit. When the return valve is activated, the dosing system will purge and return the diesel exhaust fluid in the lines to the tank.

Component Location:
The aftertreatment diesel exhaust fluid return valve is internal to the aftertreatment diesel exhaust fluid dosing unit and can not be serviced separately.

Conditions for Running the Diagnostics:
This diagnostic only runs when the aftertreatment diesel exhaust fluid dosing system is purging.

Conditions for Setting the Fault Codes:
The Engine Control Module (ECM) detected the aftertreatment diesel exhaust fluid return valve voltage was out of range low.

Action Taken When the Fault Code is Active:
1) The ECM illuminates the amber CHECK ENGINE lamp and/or the Malfunction Indicator Lamp (MIL) immediately when the diagnostic runs and fails.
2) Diesel exhaust fluid injection into the aftertreatment system is disabled.
3) Engine torque will be reduced if the engine is operated for an extended period of time with this fault active.

Conditions for Clearing the Fault Code:
1) To validate the repair, perform a key cycle, start the engine and let it idle for 1 minute.
2) The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.
3) The ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.
4) For On-Board Diagnostics (OBD) engines, the ECM will extinguish the Malfunction Indicator Lamp (MIL) after three consecutive trips where the diagnostic runs and passes.
5) The Reset All Faults command in INSITE™ electronic service tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.

Shop Talk:
If this fault is active, the dosing system may not be able to purge, which means there will be diesel exhaust fluid left in the lines. Care must be taken when removing connections. Also, lines could freeze and become damaged in cold weather if the system is not properly purged.

Reference the appropriate OEM wiring diagram when troubleshooting circuits that utilize wiring supplied by the OEM.

For intermittent power supply and datalink communication issues with Aftertreatment Components, it is highly recommended that the OEM Power Distribution Center fuses and relays be thoroughly checked for loose, missing or intermittent connections.

Possible Causes:
1) Inactive fault codes
2) Damaged aftertreatment DEF return valve and electrical connections
3) Faulty ECM
4) Faulty OEM harness
5) Open circuit
6) Pin-to-pin short circuit

Reason:
Aftertreatment SCR Catalyst Conversion Efficiency – Data Valid But Below Normal Operating Range – Moderately Severe Level. NOx conversion across the SCR catalyst is too low.

Effect:
Possible reduced engine performance.

Circuit Description:
The engine control module (ECM) monitors the NOx concentration in the engine’s exhaust gases using an aftertreatment intake NOx sensor and an aftertreatment outlet NOx sensor. By comparing these two values, the ECM is able to determine the conversion efficiency of the SCR catalyst and dosing system.

Component Location:
The SCR catalyst is located in the vehicle’s exhaust system, after the diesel particulate filter and decomposition tube.

Conditions for Running the Diagnostics:
This diagnostic has to meet specific engine and aftertreatment conditions to run and complete.

Conditions for Setting the Fault Codes:
The Engine Control Module (ECM) detected the NOx conversion across the SCR catalyst was less than expected.

Action Taken When the Fault Code is Active:
1) The ECM illuminates the amber CHECK ENGINE lamp and/or the Malfunction Indicator Lamp (MIL) immediately when the diagnostic runs and fails.
2) Engine torque will be reduced if the engine is operated for an extended period of time with this fault active.

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).

Shop Talk:
Troubleshoot all other active NOx sensor and SCR dosing system related fault codes before this fault.

Possible Causes:
1) Malfunctioning diesel exhaust fluid dosing system
2) Exhaust system leaks
3) Malfunctioning SCR catalyst
4) Degraded, diluted, or incorrect diesel exhaust fluid
5) Diesel exhaust fluid deposits in the decomposition tube

Reason:
Aftertreatment Outlet NOx Sensor Heater – Abnormal Rate of Change. The aftertreatment outlet Nox sensor heater is unable to maintain its normal operating temperature.

Effect:
None on performance.

Circuit Description:
The aftertreatment outlet NOx (nitrogen oxides) sensor is a smart device and communicates with the engine control module (ECM) via the J1939 data link. The aftertreatment outlet NOx sensor performs its own internal diagnostics and reports malfunctions back to the primary ECM using the J1939 data link. The NOx sensor is permanently attached to the NOx control module.

They are serviced as a single component and can not be replaced individually. The aftertreatment outlet NOx sensor is used to measure the NOx emissions at the outlet of the aftertreatment system.

Component Location:
The aftertreatment outlet NOx sensor location can vary depending on engine application. It is usually located in the exhaust system at the outlet of the selective catalytic reduction (SCR) catalyst.

Conditions for Running the Diagnostics:
This diagnostic runs when the aftertreatment SCR outlet temperature has been above 200°C [392° F] for a calibratible period of time while the engine is running

Conditions for Setting the Fault Codes:
The Engine Control Module (ECM) detected the NOx sensor heater was unable to maintain its normal operating temperature.

Action Taken When the Fault Code is Active:
The ECM illuminates the amber CHECK ENGINE lamp and/or the Malfunction Indicator Lamp (MIL) immediately when the diagnostic runs and fails.

Conditions for Clearing the Fault Code:
1) To validate the repair, start and operate the engine to raise exhaust temperatures. This can be done by either driving the vehicle or initiating a stationary regeneration using INSITE™ electronic service tool.
2) The aftertreatment SCR outlet temperature must be above 200° C [392° F] for 60 seconds before the aftertreatment outlet NOx sensor can run its internal diagnostics.
3) The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.
4) The ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.
5) For On-Board Diagnostics (OBD) engines, the ECM will extinguish the Malfunction Indicator Lamp (MIL) after three consecutive trips where the diagnostic runs and passes.
6) The Reset All Faults command in INSITE™ electronic service tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.

Shop Talk:
The NOx sensor heater is internal to the NOx sensor assembly, and can not be serviced separately.

Reference the appropriate OEM wiring diagram when troubleshooting circuits that utilize wiring supplied by the OEM.

For intermittent power supply and datalink communication issues with Aftertreatment Components, it is highly recommended that the OEM Power Distribution Center fuses and relays be thoroughly checked for loose, missing or intermittent connections.

Possible Causes:
1) A damaged aftertreatment outlet NOx sensor
2) Intermittent power connection to the aftertreatment outlet NOx sensor

Reason:
Aftertreatment Diesel Exhaust Fluid Pressure Sensor – Data Erratic, Intermittent, or Incorrect. The diesel exhaust fluid pressure sensor has reported a reading too high or low for the operating conditions.

Effect:
Possible reduced engine performance.

Circuit Description:
The Engine Control Module (ECM) provides a 5 volt supply and a ground to the aftertreatment diesel exhaust fluid pressure sensor. The pressure sensor provides a signal to the ECM on the sensor signal circuit. This sensor signal voltage changes, based on the aftertreatment diesel exhaust fluid pressure supplied by the dosing unit. The ECM will detect a low signal voltage at low diesel exhaust fluid pressures, and a high signal voltage at high diesel exhaust fluid pressures.

Component Location:
The aftertreatment diesel exhaust fluid pressure sensor is internal to the aftertreatment diesel exhaust fluid dosing unit and can not be serviced separately.

Conditions for Running the Diagnostics:
This diagnostic runs when diesel exhaust fluid dosing unit is fully primed, and is actively maintaining diesel exhaust fluid pressure in the dosing system.

Conditions for Setting the Fault Codes:
The diesel exhaust fluid dosing unit was unable to maintain the commanded diesel exhaust fluid pressure.

Action Taken When the Fault Code is Active:
1) The ECM illuminates the amber CHECK ENGINE lamp and/or Malfunction Indicator Lamp (MIL) after the diagnostic fails on two consecutive trips.
2) Engine torque will be reduced if the engine is operated for an extended period of time with this fault active.

Conditions for Clearing the Fault Code:
1) To validate the repair, perform the “Aftertreatment Diesel Exhaust Fluid Doser Pump Override Test” found under “ECM Diagnostic Tests” in the INSITE™ electronic service tool.
2) The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.
3) The ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.
4) For On-Board Diagnostics (OBD) engines, the ECM will extinguish the Malfunction Indicator Lamp (MIL) after three consecutive trips where the diagnostic runs and passes.
5) The Reset All Faults command in INSITE™ electronic service tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.

Shop Talk:
Reference the appropriate OEM wiring diagram when troubleshooting circuits that utilize wiring supplied by the OEM.

For intermittent power supply and datalink communication issues with Aftertreatment Components, it is highly recommended that the OEM Power Distribution Center fuses and relays be thoroughly checked for loose, missing or intermittent connections.

Possible Causes:
1) Leaking diesel exhaust fluid lines
2) Malfunctioned or malfunctioning diesel exhaust fluid dosing unit
3) Blocked or restricted diesel exhaust fluid dosing unit supply line fitting
4) Blocked or restricted diesel exhaust fluid filters
5) Malfunctioning diesel exhaust fluid pressure sensor

Reason:
Engine VGT Nozzle Position – Mechanical System Not Responding or Out of Adjustment. The smart VGT controller has detected incorrect stop limits or the VGT is unable to move to the closed position.

Effect:
Possible reduced engine performance.

Circuit Description:
The variable geometry turbocharger (VGT) is electronically activated by the VGT actuator. The VGT actuator is a smart device and receives information via the J1939 data link from the primary engine control module (ECM). The VGT actuator performs its own diagnostics and reports malfunctions back to the primary engine ECM, using the J1939 data link. The ECM then decodes the error message and converts it to a fault code.

Component Location:
The VGT actuator is located on the turbocharger bearing housing.

Conditions for Running the Diagnostics:
This diagnostic runs at initial key ON and occasionally during engine operation. The keyswitch must be turned OFF for more than 30 seconds before this diagnostic will run at initial key ON.

Conditions for Setting the Fault Codes:
The Variable Geometry Turbocharger (VGT) actuator position could not meet the commanded position for greater than 10 seconds.

Action Taken When the Fault Code is Active:
1) The ECM logs the fault code immediately when the diagnostic runs and fails.
2) The VGT actuator will continue to attempt to meet the commanded position.

Conditions for Clearing the Fault Code:
1) To validate the repair, perform a key cycle, and leave the keyswitch in the ON position for 1 minute. Note that the keyswitch must be completely turned OFF for more than 30 seconds before this diagnostic will run at initial key ON.
2) The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.
3) The Reset All Faults command in INSITE™ electronic service tool can be used to clear active and inactive faults.

Shop Talk:
This is an informational fault code indicating that the VGT actuator was unable to go to the desired position at key ON. While active, the ECM will continuously attempt to restore normal VGT operation until the engine coolant temperature reaches 74°C [165°F]. If the condition continues to exist after the coolant reaches 74°C [165°F], Fault Code 2387 will become active and Fault Code 3616 will become inactive. Fault Code 2346 may set due to a resulting fueling derate. Large boost pressure leaks can also cause this fault code.

Possible Causes:
1) Inactive fault codes
2) Faulty turbocharger assembly
3) Faulty ECM