PACCAR PX-9 CM2350 (2013-17) Fault Code:334 PID:110 SPN:110 FMI:2 Engine Coolant Temperature – Data Erratic, Intermittent, or Incorrect

Reason:
Engine Coolant Temperature – Data Erratic Intermittent or Incorrect. The engine coolant temperature sensor is reading an erratic value at initial key ON.

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:
The engine must be turned OFF for period of 8 hours before this diagnostic will run. This diagnostic runs when the keyswitch is turned to the ON position after an 8 hour cold soak.

Conditions for Setting the Fault Codes:
The Engine Control Module (ECM) detected the engine coolant temperature was greater than other engine temperature sensors by a calibratable value.

Action Taken When the Fault Code is Active:
1) The ECM illuminates the amber CHECK ENGINE lamp and/or Malfunction Indicator Lamp (MIL) after the diagnostic fails on two consecutive trips.
2) A default value is used for the engine coolant temperature reading.

Conditions for Clearing the Fault Code:
1) To validate the repair, the engine must be shut down with the keyswitch in the OFF position for 8 hours. After the 8 hour cold soak, 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:
N/A

Possible causes of this fault code include:
1) In-range malfunction of the engine coolant temperature sensor
2) High resistance in the engine coolant temperature sensor signal or return lines.