Cummins ISB4.5 CM2150 Fault Code: 491 PID: SID 88 SPN: 1189 FMI: 3 Turbocharger 2 Wastegate Control Circuit – Voltage Above Normal or Shorted to High Source.

Posted by PerDiezel Solutions on January 20, 2026

Circuit Description
The wastegate actuators are devices used by the ECM to control boost pressure.

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

Conditions for Setting the Fault Codes
The turbocharger 2 wastegate control signal is detected to be at system voltage when the voltage is turned off.

Action Taken When the Fault Code is Active
The ECM illuminates the amber CHECK ENGINE light immediately when the diagnostic runs and fails.

Conditions for Clearing the Fault Code
The ECM will turn off the amber CHECK ENGINE light immediately after the diagnostic runs and passes.

Possible Causes
-A short circuit to voltage source in the harness
-An open circuit in the harness, connector, or wastegaste control valve.

Cummins ISB4.5 CM2150 Fault Code: 478 PID: 444 SPN: 444 FMI: 0 Battery 2 Voltage – Data Valid but Above Normal Operating Range – Moderately Severe Level.

Cummins ISB4.5 CM2150 Fault Code: 477 PID: 444 SPN: 444 FMI: 1 Battery 2 Voltage – Data Valid but Below Normal Operating Range – Moderately Severe Level.

Cummins ISB4.5 CM2150 Fault Code: 471 PID: SPN: 98 FMI: 17 Engine Oil Level – Data Valid but Below Normal Operating Range – Least Severe Level.

Cummins ISB4.5 CM2150 Fault Code: 466 PID: SID 32 SPN: 1188 FMI: 4 Turbocharger 1 Wastegate Control Circuit – Voltage Below Normal or Shorted to Low Source.

Cummins ISB4.5 CM2150 Fault Code: 465 PID: SID 32 SPN: 1188 FMI: 3 Turbocharger 1 Wastegate Control Circuit – Voltage Above Normal or Shorted to High Source.

Cummins ISB4.5 CM2150 Fault Code: 452 PID: SPN: 157 FMI: 4 Injector Metering Rail 1 Pressure Sensor Circuit – Voltage Below Normal or Shorted to Low Source.

WARNING!