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Home >> Chevrolet >> 2001 >> Camaro Base, 2D Convertible, Automatic >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 2 (Engine Control System Self-Diagnostics - 5.7L) >> Diagnostic Tests >> DTC P0171: Fuel Trim System Lean - Bank 1; P0174: Fuel Trim System Lean - Bank 2 >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different variant/trim than selected.
  1. If powertrain diagnostic system check was performed, go to next step. If powertrain diagnostic system check was not performed, go to POWERTRAIN DIAGNOSTIC SYSTEM CHECK  under DIAGNOSTIC SYSTEM TESTS. After performing powertrain diagnostic system check, go to next step.
    NOTE: If other DTCs are present, except P0171 or P0174, diagnose those DTCs first. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .
  2. Start engine and run to normal operating temperature. Ensure system is in closed-loop. Using scan tool, record long term fuel trim. Turn engine off. Turn ignition on. Review FREEZE FRAME and/or FAILURE RECORDS for DTC. If long term fuel trim is less than 23 percent, go to DIAGNOSTIC AIDS . If long term fuel trim is more than 23 percent, go to next step.
  3. Start engine and allow to idle. Observe suspect HO2S using scan tool. If HO2S reading is fluctuating between 200 mV and 800 mV, go to next step. If HO2S reading is not fluctuating or not between 200 mV and 800 mV, go to step  5.
  4. Turn engine off. Visually check for damaged or improperly routed/connected vacuum hoses. DTC will set if fuel pressure is too low. Check that fuel tank has adequate fuel to run diagnostics. Check for contaminated fuel. Repair condition as necessary. After repairs, go to step  7. If conditions are not found, go to step  6.
  5. Check for proper installation of suspect HO2S. Ensure HO2S harness is not contacting exhaust system. Check for short between HO2S wires. Repair as necessary. After repairs, go to step  7. If conditions are not found, diagnose fuel system. See appropriate SYSTEM & COMPONENT TESTING article.
  6. With engine operating at idle, check for the following conditions:
    • Missing, loose or leaking exhaust components before HO2S.
    • Vacuum leaks at throttle body, injector "O" rings or intake manifold.
    • Air leaks in air induction system.
    • Leaks in AIR system, improper air delivery to AIR system or malfunctioning shutoff valves.
    • Leaking crankcase ventilation system.

    Repair as necessary. After repairs, go to next step. If conditions are not found, diagnose engine mechanical condition. Repair engine mechanical condition as necessary.

    NOTE: After performing any repairs, use fuel trim reset function on scan tool to reset long term fuel trim.
  7. Using scan tool, select FUEL TRIM RESET function to reset long term fuel trim and clear DTCs. Turn ignition off for at least 30 seconds. Start engine and allow it to reach normal operating temperature. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, go to step  2.
  8. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no undiagnosed DTCs are displayed, system is okay.
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