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Diagnosis & Repair

  1. Inspect all air induction components. Repair as necessary. Connect scan tool. See Figure. Start engine and warm to normal operating temperature. Monitor heated oxygen sensor output voltage and short-term fuel trim.
  2. If scan tester indicates a lean condition (.55 volts or less, +20 trim) or rich condition (.4 volts or more, -20 trim), go to next step. If results are other than shown, see CODE P0130, HEATED OXYGEN SENSOR FAULT (BANK NO. 1, SENSOR NO. 1), CODE P0150, HEATED OXYGEN SENSOR FAULT (BANK NO. 2, SENSOR NO. 1) diagnostic test.
  3. Inspect fuel pressure. See BASIC TESTING article. Repair as necessary. If fuel pressure is okay, inspect fuel injector performance. See SYSTEM/COMPONENT TESTS article. Replace injectors as necessary.
  4. If all injectors are okay, inspect Mass Airflow (MAF) sensor and Engine Coolant Temperature (ECT) sensor. See appropriate SYSTEM/COMPONENT TESTS article. Replace as necessary. If both components are okay, inspect ignition system. See BASIC TESTING article. Repair as necessary. If ignition system is okay, replace ECM and retest.
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