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Home >> Oldsmobile >> 2003 >> Bravada AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Self-Diagnostics - 4.2L >> Diagnostic Tests >> DTC P1171: Fuel System Lean During Acceleration >> 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, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM.
  2. Operate engine at normal operating temperature. Operate engine at greater than 1200 RPM for 2 minutes. Observe the HO2S 1 voltage parameter with a scan tool. Does the scan tool indicate that the HO2S 1 voltage is less than 300 mV? If yes, go to step  4. If no, go to next step.
  3. Observe the Freeze Frame/Failure Records for this DTC. Turn ignition off for 30 seconds. Start 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 next step. If no, go to DIAGNOSTIC AIDS .
  4. Turn ignition off. Disconnect the HO2S sensor. Turn ignition on, with engine off. Measure the voltage of the HO2S 1 high signal circuit on the PCM side with the DVOM. Does the voltage measure within 350-550 mV? If yes, go to step  6. If no, go to next step.
  5. Test the HO2S 1 high signal circuit for a short to ground or a short to the HO2S 1 low signal circuit. Did you find and correct the condition? If yes, go to step  11. If no, go to step  8.
  6. The HO2S 1 is detecting a lean condition or may be contaminated. Inspect HO2S connector for water intrusion, silicone contaminated HO2S, exhaust leak between HO2S 1 and engine, vacuum leaks, incorrect fuel pressure, or lean fuel injectors. Repair any of the conditions as necessary. Did you find and correct the condition? If yes, go to step  11. If no, go to next step.
  7. Inspect for poor connections at the harness connector of the HO2S 1 sensor. Did you find and correct the condition? If yes, go to step  11. If no, go to step  9.
  8. Inspect for poor connections at the PCM harness connector. Did you find and correct the condition? If yes, go to step  11. If no, go to step  10.
    9. NOTE: Before replacing the HO2S, determine and remove any source of contamination.
  9. Replace HO2S 1. After replacing sensor, go to step  11.
  10. Replace PCM. See REMOVAL & INSTALLATION - BRAVADA, ENVOY, ENVOY XL, TRAILBLAZER & TRAILBLAZER EXT article. Reprogram PCM. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  11. Clear the DTCs with scan tool. Turn ignition off for 30 seconds. Start engine. Operate vehicle within the Conditions For Running DTC. See CONDITIONS FOR RUNNING DTC . You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Does the DTC run and pass? If yes, go to next step. If no, go to step  2.
  12. Observe the stored information, Capture Info with scan tool. Does scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
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