GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2007 🢒 Sierra Denali 🢒 DTC 🢒 DTC P0181

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC P0181:  Fuel Temperature Sensor Performance

Circuit/System Description

The fuel temperature sensor is a thermistor. The engine control module (ECM) supplies the fuel temperature sensor a bias voltage of 5 volts on the signal circuit and also provides a low reference circuit to the sensor. When the fuel temperature sensor is cold, the resistance is high. The fuel temperature sensor signal voltage remains near the bias voltage cold and decreases as the sensor warms. The ECM monitors the fuel temperature sensor signal circuit in order to calculate the temperature of the fuel entering the engine.

Conditions for Running the DTC
    • DTCs P0182 and P0183 are not set.
    • The ignition must be turned OFF for 10 hours or longer.
    • The intake air temperature (IAT) sensor 1 is more than 10°C (50°F) at start-up.
    • DTC P0181 will only run once per ignition cycle until a Pass, Fail, or Disable conditions exists.

Conditions for Setting the DTC
    • The fuel temperature and the IAT Sensor 1 are more than 100°C (180°F) of each other at start-up.
        OR
    • The fuel temperature and the IAT Sensor 1 are more than 10°C (18°F) of each other at start-up.
        AND
    • The IAT has dropped more than 2.5°C (4.5°F) after running more than 6 minutes above 24 km/h (15 mph).

Action Taken When the DTC Sets

DTC P0181 is a Type C DTC.

Conditions for Clearing the MIL/DTC

DTC P0181 is a Type C DTC.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

    •  Engine Control Module Connector End Views
    •  Engine Controls Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

    •  Scan Tool Data List
    •  Scan Tool Output Controls
    •  Scan Tool Data Definitions

Circuit/System Verification

Important: If DTC P0182, P0183, or P2199 are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle .

  1. Turn ON the ignition and observe the Fuel Temperature Sensor parameter with a scan tool. The fuel temperature parameter should be within -30 to +120°C (-22 to +248°F).
  2. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing
  1. Ignition OFF, disconnect the harness connector at the fuel temperature sensor.
  2. Ignition OFF for 90 seconds, test for less than 5 ohms of resistance between the low reference circuit terminal 2 and ground.
    3. ⇒If greater than the specified value, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
  3. Ignition ON, verify the scan tool Fuel Temperature Sensor parameter is less than -39°C (-38°F).
    4. ⇒If greater than the specified value, test the signal circuit terminal 1 for a short to ground. If the circuit tests normal, replace the ECM.
  4. Install a 3A fused jumper wire between the signal circuit terminal 1 and a ground, Verify the scan tool Fuel Temperature Sensor parameter is greater than 120°C (248°F).
    5. ⇒If less than the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.
  5. If all circuits test normal, test fuel temperature sensor.

Component Testing
  1. Ignition OFF, disconnect the harness connector at the fuel temperature sensor.
  2. Measure and record the resistance between the signal terminal 1 and the low reference circuit terminal 2 at the fuel temperature sensor. Compare the value to the Temperature vs. Resistance table. Refer to Temperature Versus Resistance .
    3. ⇒If the sensor does not closely match through the temperature ranges, replace the fuel temperature sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Fuel Temperature Sensor Replacement