Cummins ISB CM850 (2003-06) Fault Code: 122 PID: 102 SPN: 102 FMI: 3 Intake Manifold Pressure Sensor Circuit – Voltage Above Normal or Shorted to High Source. High signal voltage detected at the intake manifold pressure circuit.

Posted by PerDiezel Solutions on January 18, 2026

The intake manifold pressure sensor shares SUPPLY and RETURN wires in the engine harness with other sensors. Opens and shorts in the engine harness can cause multiple fault codes to be active. Before troubleshooting Fault Code 122, check for multiple faults.

Possible causes:

1)Open return circuit in the engine harness, connectors, or sensor
2)SIGNAL wire shorted to sensor supply or battery voltage.

The sensor return configuration for Euro 4 ISB engines has been changed for automotive wiring harnesses manufactured from February 2012 onwards. The new style wiring harnesses can be be identified using the method below:

1)Disconnect the ECM connector
2)Disconnect the camshaft position sensor
3)Disconnect the intake manifold pressure/temperature sensor
4)Check for continuity between the intake manifold pressure/temperature sensor RETURN pin and the camshaft position sensor RETURN pin
5)Check for continuity between ECM pin 47 and the camshaft position sensor RETURN pin
6)Use the table below to determine which harness is fitted to the engine.

NOTE: QSB engines, all C series engines, and all L series engines are not affected by this change.

Possible repairs:

1)Replace the intake manifold pressure sensor.
2)Replace the ECM.
3)Replace the engine harness.

Cummins ISB CM850 (2003-06) Fault Code: 115 PID: 190 SPN: 612 FMI: 2 Engine Magnetic Crankshaft Speed/Position Lost Both of Two Signal – Data Erratic, Intermittent, or Incorrect. The ECM has detected that the primary engine speed sensor and the backup engine speed sensor signals are reversed.

Cummins ISB CM850 (2003-06) Fault Code: 111 PID: SID 254 SPN: 629 FMI: 12 Engine Control Module – critical internal failure. Error internal to the ECM related to memory hardware failures or internal ECM voltage supply circuits.

Cummins ISB CM850 (2003-06) Fault Code: FC0006 PID: SPN: FMI: Exhaust Gas Temperature Sensor Number 1 Circuit – Voltage Above Normal, or Shorted to High Source. High signal voltage or open circuit detected at the Exhaust Gas Temperature Sensor circuit.

Cummins ISB CM850 (2003-06) Fault Code: FC0005 PID: SPN: FMI: Exhaust Gas Temperature Sensor Number 1 Circuit – Voltage Below Normal, or Shorted to Low Source. Low signal voltage or open circuit detected at the Exhaust Gas Temperature Sensor circuit.

Cummins ISB CM850 (2003-06) Fault Code: FC0004 PID: SPN: FMI: Exhaust Gas Temperature Sensor Number 1 Circuit – Data Erratic, Intermittent, or Incorrect. The exhaust gas treatment monitor unit has detected that the exhaust gas temperature sensor number 1 is not changing.

Cummins ISB CM850 (2003-06) Fault Code: FC0003 PID: SPN: FMI: Exhaust Gas Pressure Sensor Number 1 Circuit – Data Erratic, Intermittent, or Incorrect. The exhaust gas treatment monitor unit has detected that the exhaust gas pressure sensor number 1 is not changing.

WARNING!