LEMON Manuals: Even more car manuals for everyone
Home >> Chevrolet >> 2012 >> Cruze Eco, Automatic Trans >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 5 (Engine Controls/Fuel - 1.8L - DTC Diagnostics, Troubleshooting & Diagnosis) >> Diagnostic Information and Procedures >> DTC P0171 or P2097 (LUW) >> Circuit/System Verification

Circuit/System Verification

WARNING: This page is about a different variant/trim than selected.
NOTE:

Disregard any transmission symptoms, antilock brake system (ABS) indicators, and traction control system indicators until any fuel trim faults are repaired. A fuel trim fault may cause default actions such as harsh shifts and illumination of the ABS/traction control system indicators.

  1. Verify that other DTCs are not set.
  2. The normal scan tool Short Term Fuel Trim parameter should be between +10 to -10%, with near 0% the optimum, with the engine running at operating temperature.
  3. The scan tool Long Term Fuel Trim parameter should be between +10 to -10%, with near 0% the optimum, with the engine running at operating temperature.
    • If the values are not less than 10%, inspect for the following:
    • With the ignition ON and the engine OFF, observe the scan tool MAP Sensor parameter. The scan tool MAP Sensor pressure reading should be within the range specified for your altitude. Refer to Altitude Versus Barometric Pressure .
      • If the B74 Manifold Absolute Pressure Sensor does not indicate the correct barometric pressure, refer to DTC P0106 (LUW) .
    • With the engine idling and the transmission in the park or neutral position, observe the scan tool MAP Sensor parameter. The scan tool MAP Sensor parameter should be between 19-42 kPa (2.8-6.1 PSI).
    • With the engine idling and the transmission in the park or neutral position, observe the scan tool MAF Sensor parameter. The scan tool MAF Sensor parameter should be between 1 700-2 100 Hz.
    • Vacuum hoses for splits, kinks, and improper connections
    • Insufficient amount of fuel in the tank
    • Low fuel pressure-Refer to Fuel System Diagnosis .
    • Fuel contamination-Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
    • Malfunctioning fuel injectors-Refer to Fuel Injector Diagnosis .
    • Missing, loose, or leaking exhaust components from the HO2S forward-Refer to Symptoms - Engine Exhaust .
    • Vacuum leaks at the intake manifold, the throttle body, the brake booster hose, and the injector O-rings
    • The air induction system and the air intake ducts for leaks or for a missing air filter element
    • A cracked EVAP canister
    • Evaporative pipes obstructed or leaking
    • The crankcase ventilation system for leaks-Refer to Crankcase Ventilation System Inspection/Diagnosis .
    • The HO2S for improper installation and for electrical wires or connectors that may have contacted the exhaust system
      • If you find any of the above conditions, repair as necessary.
  4. If all conditions test normal, test the engine for a mechanical condition. Refer to Symptoms - Engine Mechanical .
  5. Operate the vehicle within the conditions for running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the freeze frame/failure records data.
scientia non olet · About LEMON Manuals