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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 P0171 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 the displayed data for this DTC. Select Fuel and Emission data list. Start engine. Observe the Long Term FT parameter with a scan tool. Does the scan tool indicate that the Long Term FT parameter is greater than 29 percent? If yes, go to next step. If no, go to DIAGNOSTIC AIDS .
  4. Operate engine at idle. Observe the O2S parameters with a scan tool. Does the scan tool indicate that the O2S parameters 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 for splits, kinks, or improper connections at the vacuum hoses. Check for low fuel pressure. Did you find and correct the condition? If yes, go to step  9. If no, go to step  8.
  6. Turn engine off. Turn ignition on, with engine off. Observe the MAP sensor pressure parameter with a scan tool. The MAP sensor pressure should be within the range specified for your altitude. Refer to Altitude vs Barometric Pressure table in SENSOR OPERATING RANGE CHARTS - TRUCKS article. Does the MAP parameters indicate the correct barometric pressure? If yes, go to next step. If no, go to DTC P0105: MAP SENSOR CIRCUIT RANGE/PERFORMANCE .
  7. Turn engine off. Inspect for proper O2S installation. Ensure electrical connectors and wires are secured and not contacting the exhaust system. Check for short between the signal circuit and low reference or ground 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. Turn ignition off. Replace ECM. Perform ECM relearn procedure. See ELECTRONIC CONTROL MODULE REPROGRAMMING  under PROGRAMMING. After replacing ECM, go to next step.
  9. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Operate vehicle within the conditions for running the DTC. See CONDITIONS FOR RUNNING DTC . You may also operate vehicle within the conditions 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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