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Home >> Chevrolet >> 2010 >> Traverse LT, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 517 (Engine Controls And Fuel - 3.6L (LLT) - DTC P0010 To DTC P0336) >> Diagnostic Information and Procedures >> DTC P0171, P0172, P0174, or P0175: Fuel Trim System >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2016 GMC Acadia, 2016 Chevrolet Traverse, and 2016 Buick Enclave. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition ON.
  2. Verify no other DTCs are set.
    • If no other DTCs are set 
  3. Verify the MAP sensor pressure parameter is within the range specified for your altitude. Refer to Altitude Versus Barometric Pressure .
    • If not within the specified range 

      Refer to DTC P0106 .

    • If within the specified range 
    4. NOTE:

    Fuel vapor introduced into the intake manifold during evaporative emission system purge can temporarily cause fuel trim parameter readings to be outside the normal range.

  4. Engine running at the operating temperature, EVAP Purge Solenoid Valve Command 0%.
  5. Verify the appropriate Long Term Fuel Trim Bank 1 or 2 parameter is between -20% and +20%.
    • If greater than +20% 
    1. Ignition OFF.
    2. Verify the conditions listed below do not exist:
      • Mass air flow sensor signal skewed. If the Short Term Fuel Trim or Long Term Fuel Trim parameters for both banks changes greater than 20% when the MAF sensor is disconnected, refer to DTC P0101 .
      • Verify the EVAP Purge Solenoid Valve is commanded to 0%
      • Fuel contamination. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
      • Missing, restricted, or leaking exhaust components. Refer to Symptoms - Engine Exhaust .
      • Malfunctioning fuel injectors. Refer to Fuel Injector Solenoid Coil Test .
      • Split, kinked, or improperly connected vacuum hoses.
      • Insufficient fuel in the tank.
      • Low fuel pressure. Refer to Fuel System Diagnosis .
      • Vacuum leaks at the intake manifold, the throttle body, and the injector O-rings.
      • Leaks in the air induction system and the air intake ducts, including mechanical sound enhancer, if equipped.
      • Missing air filter element.
      • Cracked evaporative emissions canister.
      • Evaporative pipes obstructed or leaking.
      • Leaks in the crankcase ventilation system. Refer to Crankcase Ventilation System Inspection/Diagnosis .
        • If a condition is found, repair as necessary.
        • If no condition is found, test the engine for a mechanical condition. Refer to Symptoms - Engine Mechanical .
    • If less than -20% 
    1. Ignition OFF.
    2. Verify the conditions listed below do not exist:
      • Mass air flow (MAF) sensor signal skewed. If the Short Term Fuel Trim or Long Term Fuel Trim parameters for both banks changes greater than 20% when the MAF sensor is disconnected, refer to DTC P0101 .
      • Fuel contamination. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
      • Missing, restricted, or leaking exhaust components. Refer to Symptoms - Engine Exhaust .
      • Malfunctioning fuel injectors. Refer to Fuel Injector Solenoid Coil Test .
      • Collapsed or restricted air intake duct.
      • Excessive fuel pressure. Refer to Fuel System Diagnosis .
      • Dirty or restricted air filter.
      • Objects blocking the throttle body.
      • Improper operation of the evaporative emissions control system.
      • Excessive fuel in the crankcase. Change the engine oil as necessary.
        • If a condition is found, repair as necessary.
        • If no condition is found, test the engine for a mechanical condition. Refer to Symptoms - Engine Mechanical .
    • If between -20% and +20% 
  6. All OK.
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