Overview

Code

Fault Code: 212

PID: P175

SPN: 175

FMI: 3/3

LAMP: Amber

SRT:      

Reason

High signal voltage or an open circuit detected at the engine oil temperature circuit.

Effect

None on performance.

Engine Oil Temperature Sensor Circuit

Circuit Description

The engine oil temperature sensor is a variable resistor sensor and is used to measure the temperature of the engine oil. 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.

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 out of range high.

Action Taken When the Fault Code is Active

• The ECM illuminates the amber CHECK ENGINE lamp and/or the malfunction indicator lamp (MIL) immediately when the diagnostic runs and fails.

A default value for the engine oil temperature reading is used.

Conditions for Clearing the Fault Code

• To validate the repair, perform a key cycle, start the engine and let it idle for 1 minute.
• The fault code status displayed by the recommended Cummins electronic service tool or equivalent 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.
• 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.
• The “Reset All Faults” command in the recommended Cummins electronic service tool or equivalent 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 of this fault code include:

• Open return circuit in the harness, connectors, or sensor

Open signal circuit or shorted to a voltage source.

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