GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2006 🢒 Savana - AWD 🢒 Engine 🢒 Engine Controls - 6.6L 🢒 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 control module 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 1 are more than 100°C (180°F) of each other at start-up.
        OR
    • The fuel temperature and the IAT 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
    • The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
    • The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

Conditions for Clearing the MIL/DTC
    • The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
    • A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
    • A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
    • Clear the MIL and the DTC with a scan tool.

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
    •  Temperature Versus Resistance

Circuit/System Verification

Important: 

   • If DTC P0182, P0183, or P2199 are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle .
   • If you cannot duplicate the condition, 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.

  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. Engine running, observe the DTC information with a scan tool. DTC P0181 should not set.
  3. 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. Disconnect the fuel temperature sensor .
  2. Turn ON the ignition, with the engine OFF.
  3. Observe the Fuel Temperature parameter with a scan tool.
    4. ⇒If the fuel temperature is less than -39° (-38.2°F), test the signal circuit for an open or high resistance.
  4. Connect a 3A fused jumper wire between the fuel temperature sensor signal circuit and the low reference circuit.
    5. ⇒If the fuel temperature is less than 120°C (248°F), test for high resistance in the signal circuit or the low reference circuit.
  5. If all circuits test normal, refer to Component Testing in this diagnostic.

Component Testing
  1. Disconnect the fuel temperature sensor and measure the resistance of the sensor with a DMM.
  2. Record the values at various fuel temperatures and compare those results to the Temperature vs. Resistance Table (Fuel Temperature).
    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