Cummins ISL CM850 (2003-06) Fault Code: 145 (Marine) PID: 110 SPN: 110 FMI: 4 Engine Coolant Temperature 1 Sensor Circuit – Voltage Below Normal or Shorted to Low Source. Low signal voltage detected at engine coolant temperature circuit.

The engine coolant temperature sensor shares return wires in the engine harness with other sensors. A shorted return can cause multiple fault codes to be active. Before troubleshooting Fault Code 145, check for multiple fault codes.

Possible causes:

1)Signal shorted to ground in the harness.
2)Signal shorted to return or ground in the sensor.

Possible repairs:

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