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Diagnostic Procedures

WARNING: This page is about a different car, the 2003 Saturn Vue. 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 .
    2. NOTE: If any DTCs are set other than DTC P0172 or P0175, diagnose affected DTC(s) before continuing this test. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .
  2. Install a scan tool. Start engine. Operate vehicle within the Conditions for Running the DTC. See CONDITIONS FOR RUNNING DTC . Record the LT FT Cruise/Accel and LT FT Idle/Decel parameter values. Turn engine off. Turn ignition on, with engine off. Review the Freeze Frame/Failure Records and record the displayed data for this DTC. Does the scan tool indicate that the LT FT Cruise/Accel parameter is less than -23 percent? If yes, go to step  4. If no, go to next step.
  3. Does the scan tool indicate that the LT FT Idle/Decel parameter is less than -8.1 percent? If yes, go to next step. If no, go to DIAGNOSTIC AIDS .
  4. Operate engine at idle. Observe the HO2S parameters with a scan tool. Does the scan tool indicate that the values are within 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 the inlet screen of the MAF sensor for blockage, vacuum hoses for splits, kinks, and proper connections, air intake duct for being collapsed or restricted, air filter for being dirty or restricted, or objects blocking the throttle body. Did you find and correct the condition? If yes, go to step  8. If no, go to step  7.
  6. Turn engine off. Inspect the HO2S for proper installation. Verify that the electrical connectors and wires are secured and are not contacting the exhaust system. Did you find and correct the condition? If yes, go to step  8. If no, diagnose fuel system. Refer to FUEL SYSTEM DIAGNOSIS under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 2.2L & 3.0L VUE article.
  7. Inspect for excessive fuel in the crankcase, EVAP control system, and fuel pressure regulator for proper operation. Did you find and correct the condition? If yes, go to next step. If no, diagnose for an engine mechanical problem.
    8. NOTE: After repairs, reset the Long Term Fuel with the scan tool Fuel Trim Reset function.
  8. Clear the DTCs with a scan tool. Turn ignition off for 30 seconds. Start engine. Operate 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. Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? If yes, diagnose affected DTC(s). See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no DTCs are displayed, system is okay.
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