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Home >> Saturn >> 2003 >> L200 Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0171: Fuel Trim System Lean - Bank 1 >> Diagnostic Procedures
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Diagnostic Procedures

  1. Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM.
  2. Are any DTCs other than P0171 also set? If yes, go to DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, go to next step.
  3. Install a scan tool. Review the Freeze Frame/Failure Records and record the displayed data for this DTC. Select Fuel and Emissions Data List. Start the engine and observe the Fuel Trim Index parameter. Does the scan tool indicate that the Fuel Trim Index parameter is more than 29%? If yes, go to next step. If no, go to DIAGNOSTIC AIDS .
  4. Operate the engine at idle. Observe the O2S parameters with a scan tool. Does the scan tool indicate that the O2S parameters are within 200-800 mV and fluctuating? If yes, go to next step. If no, go to step  6.
  5. Turn OFF the engine. Visually and physically inspect for splits, kinks, and proper connections at the vacuum hoses. Check for low fuel pressure and fuel contamination. Did you find and correct the condition? If yes, go to step  9. If no, go to step  8.
  6. Turn OFF the engine. Turn ignition on, with engine off. Observe MAP sensor pressure parameter with a scan tool. The MAP sensor pressure should be within the range specified for your altitude. Refer ALTITUDE VS. BAROMETRIC PRESSURE  table. Does the MAP parameter indicate the correct barometric pressure? If yes, go to next step. If no, go to DTC P0105: MAP SENSOR CIRCUIT RANGE/PERFORMANCE .
  7. Turn OFF the engine. Inspect for proper O2S installation, electrical connectors and wires are secured and not contacting the exhaust system, or short between the signal circuit and low reference or ground circuit. Did you find and correct the condition? If yes, go to step  9. If no, go to diagnose fuel system.
  8. Operate the engine at idle. Inspect for missing, loose, or leaking exhaust components. Inspect for vacuum leaks at the intake manifold, throttle body, and injector O-rings. Inspect leaks at the air intake ducts, or leaking crankcase ventilation system. Did you find and correct the condition? If yes, go to next step. If no, diagnose for an engine mechanical problem.
    9. NOTE: After repairs, use the scan tool Fuel Trim Reset function in order to reset the Long Term Fuel Trim.
  9. Clear the DTCs with a scan tool. Turn ignition off for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running the DTC. See CONDITIONS FOR RUNNING DTC . You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition? If yes, go to step  2. If no, go to next step.
  10. Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? If yes, go to DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
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