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.

Posted by PerDiezel Solutions on January 18, 2026

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.

Cummins ISB CM850 (2003-06) Fault Code: 434 PID: SID 251 SPN: 627 FMI: 2 Power Supply Lost With Ignition On – Data Erratic, Intermittent or Incorrect. Supply voltage to the ECM fell below 6.2 VDC momentarily, or the ECM was not allowed to power down correctly (retain battery voltage for 30 seconds after key OFF).

Cummins ISB CM850 (2003-06) Fault Code: 433 PID: 102 SPN: 102 FMI: 2 Intake manifold pressure sensor circuit – data incorrect. An error in the intake manifold pressure sensor signal was detected by the ECM.

Cummins ISB CM850 (2003-06) Fault Code: 432 PID: SID 230 SPN: 558 FMI: 13 Accelerator Pedal or Lever Idle Validation Circuit – Out of Calibration. Voltage at idle validation on-idle and off-idle circuit does not match accelerator pedal position.

Cummins ISB CM850 (2003-06) Fault Code: 431 (SSS) PID: SID 230 SPN: 558 FMI: 2 Accelerator Pedal or Lever Idle Validation Circuit – Data Erratic, Intermittent or Incorrect. Voltage detected simultaneously on both idle validation and off-idle validation switches.

Cummins ISB CM850 (2003-06) Fault Code: 431 (NISS) PID: SID 230 SPN: 558 FMI: 2 Accelerator Pedal or Lever Idle Validation Circuit – Data Erratic, Intermittent, or Incorrect. Voltage detected simultaneously on both idle validation and off-idle validation switches.

Cummins ISB CM850 (2003-06) Fault Code: 431 (ISS) PID: SID 230 SPN: 558 FMI: 2 Accelerator Pedal or Lever Idle Validation Circuit – Data Erratic, Intermittent, or Incorrect. Voltage detected simultaneously on both idle validation and off-idle validation switches.

WARNING!