Cummins ISB CM850 (2003-06) Fault Code: 144 (Marine) PID: 110 SPN: 110 FMI: 3 Engine Coolant Temperature 1 Sensor Circuit – Voltage Above Normal or Shorted to High Source. High signal voltage or open circuit detected at engine coolant temperature circuit.

Before troubleshooting Fault Code 144, check for multiple faults.

The engine coolant 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 coolant temperature sensor
2)Replace the ECM.
3)Replace the engine harness.