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

Diagnosis & Repair

  1. Inspect all air induction components. Repair as needed. Connect scan tester. See Figure and 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 (RIGHT SIDE, NO. 1) CIRCUIT .
  3. Inspect fuel pressure. See the BASIC TESTING article. Repair as needed. If fuel pressure is okay, inspect fuel injector performance. See SYSTEM/COMPONENT TESTS article. Replace as needed.
  4. If all injectors okay, inspect Mass Airflow (MAF) sensor and Coolant Temperature Sensor (CTS). See SYSTEM/COMPONENT TESTS article. Replace as needed. If both components are okay, inspect ignition system. See BASIC TESTING article. Repair as needed. If ignition system is okay, replace ECM and retest.
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