Engine Fuel Temperature Sensor 1 Circuit – Voltage Above Normal or Shorted to High Source
|Fault Code: 263
Engine Fuel Temperature Sensor 1 Circuit – Voltage Above Normal or Shorted to High Source. High signal voltage detected at engine fuel temperature circuit.
Possible low power when engine is cold.
ISX – Engine Fuel Temperature Sensor 1 Circuit
The engine fuel temperature sensor is used by the electronic control module (ECM) to monitor engine fuel temperature. Fuel temperature is used by the ECM to adjust fuel delivery to the injectors. The engine fuel temperature sensor is a thermistor and changes resistance based on the temperature being measured. The ECM provides a 5 VDC reference voltage to the sensor. The ECM monitors the change in signal voltage and converts this to a temperature value.
The engine fuel temperature sensor is located on the lower rear of the integrated fuel system module (IFSM). Refer to Procedure 100-002 (Engine Diagrams) in Section E for a detailed component location view.
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 ECM detects that the engine fuel temperature signal voltage is greater than 4.8-VDC for more than 1 second.
Action Taken When the Fault Code is Active
- The ECM illuminates the amber CHECK ENGINE light immediately when the diagnostic runs and fails.
- A default value for the engine fuel temperature reading is used.
Conditions for Clearing the Fault Code
The ECM will turn off the amber CHECK ENGINE light immediately after the diagnostic runs and passes.
Verify the electronic control module (ECM) calibration is correct. Check the calibration revision history found on QuickServe® Online for applicable fixes to the calibration stored in the ECM. If necessary, recalibrate the ECM. Refer to Procedure 019-032 (ECM Calibration Code) in Section 19 in the corresponding Troubleshooting and Repair Manual for the engine being serviced.
The engine fuel 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.