PACCAR PX-9 CM2350 (2013-17) Fault Code:212 PID:175 SPN:175 FMI:3 Engine Oil Temperature Sensor 1 Circuit – Voltage Above Normal or Shorted to High Source

Reason:
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.

Effect:
None on performance.

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 signal voltage was greater than 4.95 VDC for more than 10 second.

Action Taken When the Fault Code is Active:
1) The ECM illuminates the amber CHECK ENGINE lamp and/or the Malfunction Indicator Lamp (MIL) immediately when the diagnostic runs and fails.
2) A default value for the engine oil temperature reading is used.

Conditions for Clearing the Fault Code:
1) To validate the repair, perform a key cycle, start the engine and let it idle for 1 minute.
2) The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.
3) The ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.
4) For On-Board Diagnostics (OBD) engines, the ECM will extinguish the Malfunction Indicator Lamp (MIL) after three consecutive trips where the diagnostic runs and passes.
5) 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:
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.