Cummins ISB CM850 (2003-06) Fault Code: 435 PID: 100 SPN: 100 FMI: 2 Oil Pressure Switch Sensor Circuit – Data Erratic, Intermittent or Incorrect. An error in the engine oil pressure switch signal was detected by the ECM.

The oil pressure switch is closed with the engine not running and open when oil pressure is present. This fault code is logged when an open circuit is detected for five consecutive key cycles when the ECM expected a closed circuit at key-on.

Possible causes:

1)Failed engine oil pressure switch
2)Open circuit in the engine oil pressure switch signal wire
3)Failed ECM
4)Short circuit in the engine oil pressure switch signal wire to a voltage source.

Possible repairs:

1)Repair or replace the engine oil pressure switch.
2)Repair or replace the engine harness.
3)Replace the ECM.