Cummins X12 CM2350 X119B (2018 & Newer) Fault Code: 421 PID: PID 175 SPN: 175 FMI: 16 Engine Oil Temperature- Data Valid But Above Normal Operating Range- Moderately Severe Level

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 engine 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 cold, 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 low temperature. When the oil temperature is warm, the sensor resistance is low. The signal voltage pulls down a large amount. Therefore, the ECM senses a low signal voltage or 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
This diagnostic runs continuously when the keyswitch is in the ON position or when the engine is running.

Conditions for Setting the Fault Codes
The Engine Control Module (ECM) detected the engine oil temperature was greater than the warning engine protection limit for 5 seconds.

Action Taken When the Fault Code is Active
The ECM illuminates the amber CHECK ENGINE lamp immediately when the diagnostic runs and fails.
The torque output of the engine will be reduced.
Conditions for Clearing the Fault Code
To validate the repair using a Diagnostic Road Test, utilize a route that incorporates both stop and go city type driving and steady state highway type driving. It may be necessary to load the unit for certain diagnostics in the ECM to run.
To validate the repair using a Chassis Dynamometer, utilize a routine that incorporates acceleration and motoring events, steady state highway type operation, and load. This will simulate normal driving and allow the diagnostics in the ECM to run.
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 immediately after 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.

Shop Talk
This fault code indicates that the engine oil temperature has exceeded the warning engine protection limit for oil temperature. Troubleshoot the cause of high engine oil temperature.

Possible Cause:
1) ECM calibration