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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. 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. Are any DTCs other than P0172 also set? If yes, diagnose affected DTC(s). See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, go to next step.
  3. Install a scan tool. Review the Freeze Frame/Failure Records and record displayed data for this DTC. Select Fuel and Emission parameter. Start engine. Observe the Long Term FT parameter with a scan tool. Doe the scan tool indicate that the Long Term FT is less than -46 percent? If yes, go to next step. If no, go to DIAGNOSTIC AIDS .
  4. Start engine. Allow the engine to reach operating temperature. Put the transmission in Park or Neutral position. Turn OFF all of the accessories. Allow the engine to idle. Observe MAP sensor. Parameter with a scan tool. Is the MAP sensor parameter within 5.6-12.4 in. Hg (19-42 kPa)? If yes, go to next step. If no, go to DTC P0105: MAP SENSOR CIRCUIT RANGE/PERFORMANCE .
  5. Start and operate the engine at idle. Observe O2S 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  7.
  6. Turn engine off. Visually and physically inspect the vacuum hoses for splits, kinks, and proper connections. Check air intake duct for being collapsed or restricted, air filter for being dirty or restricted, or for objects blocking throttle body. Did you find and correct the condition? If yes, go to step  9. If no, go to next step.
  7. Turn engine off. Inspect the O2S for proper installation. Ensure electrical connectors and wires are secured and not contacting the exhaust system. Test for continuity between the signal circuit and the low reference circuit. Did you find and correct the condition? If yes, go to step  9. If no, refer to FUEL SYSTEM DIAGNOSIS in BASIC DIAGNOSTIC PROCEDURES - 2.2L & 3.0L VUE article.
  8. Inspect for excessive fuel in the crankcase, evaporative emissions control system, or fuel pressure regulator for proper operation. Ensure that all injectors are functioning properly. Did you find and correct the condition? If yes, go to next step. If no, diagnose engine mechanical problem.
    9. NOTE: After repairs, use the scan tool Fuel Trim Reset function in order to reset the Long Term Fuel Trim.
  9. Clear the DTCs with a scan tool. 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 step  2. If no, go to next step.
  10. With a scan tool, observe the stored information, 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.
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