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Diagnostic Procedures

WARNING: This page is about a different car, the 2003 Pontiac Sunfire, 2003 Pontiac Grand Am, 2003 Oldsmobile Alero, and 2003 Chevrolet Cavalier. However, it is still accessible from the selected car via links, so may be relevant.
  1. Perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check - engine controls, go to next step.
    2. NOTE: If any DTCs are set, other than P0172, refer to those DTCs before proceeding with this diagnosis. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .
  2. Connect scan tool. Review the Freeze Frame/Failure Records and record displayed data for this DTC. Select FUEL TRIM DATA parameter. Start the engine and observe the FUEL TRIM INDEX. Does the scan tool indicate that the fuel trim index is less than -46 percent? If yes, go to next step. If no, go to DIAGNOSTIC AIDS .
  3. Start the engine. Allow the engine to reach operating temperature. Put the transmission in PARK or NEUTRAL position. Turn all accessories OFF. Allow engine to idle. Observe the Manifold Absolute Pressure (MAP) sensor. Parameter using a scan tool. Is the MAP sensor parameter within the specified range? If yes, go to next step. If no, go to DTC P0105: MANIFOLD ABSOLUTE PRESSURE SENSOR PERFORMANCE/RANGE .
  4. Operate the engine at idle. Observe the oxygen sensor parameters using a scan tool. Does the scan tool indicate the values are 200-800 mV and fluctuating? If yes, go to next step. If no, go to step  6.
  5. Turn engine off. Visually and physically inspect vacuum hoses for splits, kinks, and proper connections. Check the air intake duct for being collapsed or restricted. Check the air filter for being dirty or restricted or for objects blocking throttle body. Repair as necessary. After repair, go to step  8.
  6. Turn engine off. Inspect the HO2S for proper installation. Ensure harness connectors and wires are secured and not contacting the exhaust system. Did you find and correct the condition? If yes, go to step  8. If no, diagnose fuel system. See FUEL SYSTEMS (GASOLINE) in SYSTEM & COMPONENT TESTS - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE - GASOLINE article.
  7. Check for excessive fuel in the crankcase. Check evaporative emissions control system and fuel pressure regulator for proper operation. Ensure that all injectors are functioning properly. Perform the fuel injector balance test. See FUEL INJECTOR BALANCE TEST under FUEL SYSTEMS (GASOLINE) in SYSTEM & COMPONENT TESTS - 2.2L ALERO, CAVALIER, GRAND AM & SUNFIRE article. Did you find and correct the condition? If yes, go to next step. If no, diagnose engine mechanical problem. See appropriate article in ENGINES.
    8. NOTE: After repairs, use the scan tool Fuel Trim Reset function in order to reset the Long Term Fuel Trim.
  8. Clear the DTCs using a scan tool. Turn ignition switch to OFF position 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.
  9. Using a scan tool, observe the CAPTURE INFO. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay at this time.
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