Cummins ISB4.5 CM2150 Fault Code: 425 PID: 175 SPN: 612 FMI: 2 Engine Oil Temperature – Data Erratic, Intermittent, or Incorrect.

Circuit Description
The engine oil temperature sensor is a variable resistor sensor and is used to measure the temperature of the engine oil in the oil rifle. The electronic control module (ECM) supplies 5 volts to the engine oil temperature signal circuit. The ECM monitors the change in voltage caused by changes in the resistance of the sensor to determine the engine oil temperature. When the oil temperature is low, the sensor or thermistor resistance is high. The ECM signal voltage only pulls down a small amount through the sensor to a ground. Therefore, the ECM senses a high signal voltage or a low temperature. When the oil temperature is high, the sensor resistance is low. The signal voltage pulls down a large amount. Therefore, the ECM senses a low signal voltage, or a high temperature. The engine oil temperature sensor is used to monitor the engine oil temperature. If the temperature exceeds a calibration limit, an engine protection fault code will be triggered.

Component Location
The engine oil temperature sensor is located in the oil rifle.

Conditions for Running the Diagnostics
-The first part runs when the keyswitch is turned ON and before engine speed is detected. The ECM must not see a key cycle for a period of 10 hours before this part of the diagnostic will run.
-The second part occurs when the engine is operating.

Conditions for Setting the Fault Codes
The ECM detects that the engine oil temperature is higher or lower than the other temperature sensors on the engine after an extended period of engine OFF time.

Action Taken When the Fault Code is Active
-The ECM illuminates the amber CHECK ENGINE lamp and/or the malfunction indicator lamp (MIL) after the diagnostic runs and fails on two consecutive trips.

Conditions for Clearing the Fault Code
To validate the repair, the engine must be shut down with the keyswitch in the OFF position for a period of 10 hours. After the 10 hour cold soak, start the engine and let it idle for up to 5 minutes.

-The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.
-The ECM will turn off the amber CHECK ENGINE lamp after the diagnostic runs and passes.
-For On-Board Diagnostic (OBD) engines, the ECM will turn off the MIL after three consecutive trips where the diagnostic runs and passes.
-The “Reset All Faults” command in INSITE™ electronic service tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.

Possible Causes
-Malfunctioning oil temperature sensor.
-High resistance in the engine oil temperature signal or return circuit.