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Diagnostic Procedures

WARNING: This page is about a different car, the 2002 Oldsmobile Intrigue and 2002 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.
  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.
    NOTE: If any other DTCs are set, repair DTCs before continuing with this test. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .
  2. Start engine and allow it to idle. Ensure engine is at normal operating temperature. Using scan tool, record long term fuel trim data. Turn ignition off. Turn ignition on. Using scan tool, record LONG TERM FUEL TRIM data. Turn ignition off. Turn ignition on. Using scan tool, review FREEZE FRAME RECORDS and/or FAILURE RECORDS and record data. If long term fuel trim is less than -13 percent, go to next step. If long term fuel trim is -13 percent or more, see DIAGNOSTIC AIDS .
  3. Start engine and allow it to idle. Using scan tool, observe HO2S voltage. If voltage is 200-800 millivolts and fluctuating, go to next step. If voltage is not 200-800 millivolts or is not fluctuating, go to step  5.
  4. Turn ignition off. Check Mass Airflow (MAF) sensor inlet screen for blockage. Check vacuum hoses for splits, kinks and proper routing. Check for collapsed or restricted air intake duct. Check for restricted or dirty air filter. Check for throttle body blockage. If any problems are found, repair as necessary. After repairs, go to step  7. If no problems are found, go to step  6.
  5. Turn ignition off. Ensure HO2S is installed correctly and wiring harness is not touching exhaust. If any problems are found, repair as necessary. After repairs, go to step  7. If no problems are found, diagnose fuel system. See FUEL SYSTEMS in appropriate BASIC DIAGNOSTIC PROCEDURES article.
  6. Check for excessive fuel in crankcase. Diagnose evaporative emissions control system. Check fuel pressure regulator for proper operation. See FUEL SYSTEMS in appropriate BASIC DIAGNOSTIC PROCEDURES article. Ensure all fuel injectors are functioning properly. Perform fuel injector balance test. See FUEL SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article. If any problems are found, repair as necessary. After repairs, go to next step. If no problems are found, check engine mechanical condition and repair as necessary.
  7. After repairs, using scan tool fuel trim reset function, reset long term fuel trim. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within conditions for running the DTC. See CONDITIONS FOR RUNNING DTC . If DTC runs and passes, go to next step. If DTC resets, go to step  2.
  8. Using scan tool, check for any other DTCs that are set. If no other DTCs are set, system is okay. If any other DTCs are set, repair DTCs as necessary. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .
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