Cummins ISB CM850 (2003-06) Fault Code: FC0002 PID: SPN: FMI: Exhaust Gas Pressure Sensor Number 1 Circuit – Voltage Below Normal, or Shorted to Low Source. Low signal voltage or open circuit detected at the Exhaust Gas Pressure Sensor circuit.

Possible causes:

1)Signal circuit open or shorted to ground in the exhaust gas treatment monitor harness or exhaust gas pressure sensor.
2)Supply line open or shorted to ground.
This fault code will only be present in the exhaust gas treatment monitor unit and will not be present in the engine electronic control module (ECM). The exhaust gas treatment fault code and maintenance lamps will both flash two times in sequence to alert the operator that this condition exists. The engine diagnostic lamps will not illuminate.

Possible repairs:

1)Replace the exhaust gas pressure sensor.
2)Repair or replace the exhaust gas treatment monitor harness.
3)Replace the exhaust gas treatment monitor unit.