Cummins ISB4.5 CM2150 Fault Code: 3616 PID: SPN: 2633 FMI: 7 Engine VGT Nozzle Position – Mechanical System Not Responding or Out of Adjustment.

Posted by PerDiezel Solutions on January 20, 2026

Circuit Description
The VGT is electronically activated by the VGT actuator. The VGT actuator is a smart device that receives information via the J1939 data link from the primary engine control module (ECM). The VGT actuator performs its own diagnostics and reports errors back to the primary engine ECM with the J1939 data link.

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

Conditions for Running the Diagnostics
This diagnostic runs continuously when the keyswitch is initially turned to the ON position and periodically when the engine is running.

The keyswitch must be completely turned OFF for more than 30 seconds before this diagnostic will run at initial key ON.

Conditions for Setting the Fault Codes
This fault code is set when the actual VGT actuator position does not meet the commanded position for more than 10 seconds, and the coolant temperature is below a calibrated value.

Action Taken When the Fault Code is Active
-This is a no-lamp fault. The ECM logs the fault code immediately when the diagnostic runs and fails.
-The VGT actuator will continue to attempt to meet the commanded position.

Conditions for Clearing the Fault Code
-The keyswitch must be completely turned OFF for more than 30 seconds before this diagnostic will run at initial key ON.
-The fault code will clear at key ON if the error condition no longer exists.

Shop Talk
This fault code is an information fault code indicating that the VGT turbocharger sliding nozzle was unable to go to the desired position. No troubleshooting is necessary for this fault code. It is only an indicator that the engine power can be limited due to a stuck VGT turbocharger sliding nozzle. If the condition continues to exist, Fault Code 2387 will become active. It is also possible for large boost pressure leaks to also cause this fault code to become active.

Inspect the turbocharger vanes for residue, and clean the vanes, if required. Find the source of the residue and repair.

Cummins ISB4.5 CM2150 Fault Code: 3612 PID: SPN: 3361 FMI: 7 Aftertreatment Diesel Exhaust Fluid Dosing Unit – Mechanical System Not Responding or Out of Adjustment.

Cummins ISB4.5 CM2150 Fault Code: 3598 PID: SPN: 3360 FMI: 19 Aftertreatment Diesel Exhaust Fluid Controller – Received Network Data In Error.

Cummins ISB4.5 CM2150 Fault Code: 3597 PID: SID 254 SPN: 3360 FMI: 9 Aftertreatment Diesel Exhaust Fluid Controller – Abnormal Update Rate.

Cummins ISB4.5 CM2150 Fault Code: 3596 PID: SPN: 4334 FMI: 2 Aftertreatment Diesel Exhaust Fluid Pressure Sensor – Data Erratic, Intermittent, or Incorrect.

Cummins ISB4.5 CM2150 Fault Code: 3579 PID: SPN: 4376 FMI: 5 Aftertreatment Diesel Exhaust Fluid Return Valve – Current Below Normal or Open Circuit.

Cummins ISB4.5 CM2150 Fault Code: 3578 PID: SPN: 4376 FMI: 4 Aftertreatment Diesel Exhaust Fluid Return Valve – Voltage Below Normal or Shorted to Low Source.

WARNING!