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Home >> Toyota >> 1995 >> Tercel Base, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Diagnostic Testing >> Code P0170 - Fuel Trim Malfunction >> Diagnosis & Repair
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Diagnosis & Repair

  1. Inspect all air induction components. Repair as needed. Connect scan tester. 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 volt or less, +20 trim) or rich condition (.4 volt or more, -20 trim), go to next step. If results are other than shown, see CODE P0130  - HEATED OXYGEN SENSOR (FRONT SENSOR) CIRCUIT.
  3. Inspect fuel pressure. See the BASIC TESTING article. Repair as needed. If fuel pressure is okay, inspect fuel injector performance. See the SYSTEM/COMPONENT TESTS article. Replace as needed.
  4. If all injectors are okay, inspect Mass Airflow (MAF) sensor and Coolant Temperature Sensor (CTS). See procedures in the SYSTEM/COMPONENT TESTS article. Replace as needed. If both components are okay, inspect ignition system. See procedures in the BASIC TESTING article. Repair as needed. If ignition system is okay, replace ECM and retest.
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