PACCAR PX-9 CM2350 (2013-17) Fault Code:2789 PID:110 SPN:110 FMI:18 Engine Coolant Temperature – Data Valid But Below Normal Operational Range – Moderately Severe Level

Reason:
Engine Coolant Temperature – Data Valid But Below Normal Operational Range – Moderately Severe Level. Engine coolant temperature is below normal operating temperature limits.

Effect:
None on performance

Circuit Description:
The coolant temperature sensor is a variable resistor sensor and is used to measure the temperature of the coolant of the engine. The engine control module (ECM) supplies 5 volts to the coolant temperature signal circuit. The ECM monitors the change in voltage caused by changes in the resistance of the sensor to determine the coolant temperature.

Component Location:
The engine coolant temperature sensor is located on the thermostat housing.

Conditions for Running the Diagnostics:
This diagnostic runs continuously when the engine is running.

Conditions for Setting the Fault Codes:
Engine coolant temperature was less than 60°C [140°F] for over 1 hour during a period of extended idle.

Action Taken When the Fault Code is Active:
The ECM illuminates the amber CHECK ENGINE lamp immediately when the diagnostic runs and fails.

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 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:
If this fault indicates that coolant temperature is below a calibratible limit set in the ECM. Refer to Engine Coolant Temperature Below Normal troubleshooting symptom tree tree in the base engine service manual.

Possible Causes:
1) Inactive fault codes
2) Faulty ECM