Cummins ISM CM870 (2003-06) Fault Code: 212 PID: P175 SPN: 175 FMI: 3/3 Engine Oil Temperature Sensor 1 Circuit – Voltage Above Normal or Shorted to High Source. High signal voltage or an open circuit detected at the engine oil temperature circuit.

The engine oil temperature sensor shares return wires in the engine harness with other sensors. An open return can cause multiple fault codes to be active.

Possible causes:

1)Open return circuit in the harness, connectors, or sensor.
2)Open signal circuit or shorted to a voltage source.

Possible repairs:

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