Cummins ISM CM870 (2003-06) Fault Code: 222 PID: P108 SPN: 108 FMI: 4/4 Barometric Pressure Sensor Circuit – Voltage Below Normal or Shorted to Low Source. Low signal voltage detected at barometric pressure circuit.

The barometric 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 222, check for multiple faults.

Possible causes:

1)Signal circuit open or shorted to ground in the engine harness or sensor
2)Supply wire open or shorted to ground.

Possible repairs:

1)Replace the barometric sensor.
2)Replace the ECM.
3)Repair or replace the engine harness