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Diagnostic Procedures

WARNING: This page is about a different car, the 2003 Pontiac Vibe. 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, perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM.
  2. Start engine. Operate vehicle until loop status indicates closed loop. Observe Short Term FT parameter display on scan tool. Is Short Term FT parameter displayed on scan tool more than -20 percent? If yes, go to DIAGNOSTIC AIDS . If no, go to next step.
  3. Visually and physically check air filter and air induction assembly for any of the following conditions:
    • A dirty or contaminated air filter.
    • Any restrictions or blockage of airflow.
    • Any leaks in the exhaust system.
    Did any of the above checks isolate a condition requiring a repair? If yes, go to next step. If no, go to step  9.
  4. Start engine. Run engine until engine reaches a normal operating temperature. Using a scan tool, observe operation of the following sensors at idle:
    • Mass Air Flow (MAF) sensor.
    • Engine Coolant Temperature (ECT) sensor.
    • Pre-catalyst Heated Oxygen Sensor (HO2S 1).
    Compare the observed sensor readings with Typical Scan Tool Data Values located in engine scan tool data list. See SCAN TOOL DATA LIST . Check any errant readings for their cause and repair as necessary. Was a repair necessary? If yes, go to step  9. If no, go to next step.
  5. Turn ignition OFF. Install a fuel pressure gauge. See FUEL GAUGE under FUEL SYSTEMS in REMOVAL & INSTALLATION - 1.8L VIBE article. Observe fuel pressure with engine running at a normal operating temperature. Is fuel pressure 44-50 psi (301-347 kPa)? If yes, go to next step. If no, diagnose fuel system. See FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 1.8L VIBE article.
  6. Check Evaporative Emission (EVAP) control system for possible over-purging of EVAP system. See EVAPORATIVE EMISSION CONTROL SYSTEM DIAGNOSIS in SYSTEM & COMPONENT TESTING - 1.8L VIBE article. Repair as necessary. Was a problem found? If yes, go to step  9. If no, go to next step.
  7. Remove and visually and physically check HO2S 1 for silicone contamination. Contamination will be indicated by a powdery White deposit on the portion of HO2S that is exposed to exhaust stream. If contamination is evident on HO2S, replace contaminated sensor and correct source of contamination. Did HO2S require replacement? If yes, go to step  9. If no, go to next step.
  8. Is a rich condition still present? If yes, see SYMPTOM DIAGNOSIS in TROUBLE SHOOTING - NO CODES - 1.8L VIBE article. If no, go to next step.
  9. Use scan tool to clear DTCs. Turn ignition OFF for 30 seconds. Start engine. Operate vehicle within CONDITIONS FOR RUNNING DTC . Does DTC run and pass? If yes, go to next step. If no, go to step  2.
  10. Using scan tool, observe stored information, CAPTURE INFO. Does scan tool display any DTCs that have not been diagnosed? If yes, go to DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no DTCs are displayed, system is okay at this time.
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