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Home >> Toyota >> 1997 >> Previa LE, AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Tests W/Codes >> Circuit Tests >> DTC P0125: Insufficient Coolant Temperature For Closed Loop Fuel Control >> Diagnosis & Repair
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Diagnosis & Repair

  1. Connect scan tool to DLC No. 3 connector. See Figure. Start vehicle and warm engine to normal operating temperature. Using scan tool, monitor sensor No. 1. Using accelerator pedal, snap accelerate engine 3 times (to about 4000 RPM each time). Sensor should indicate a rich signal (.45 volt or more) at least once. If a rich signal is indicated at least once, go to step 4). If sensor does not display a rich signal at least once, go to next step.
  2. Using scan tool, monitor sensor No. 1. Using accelerator pedal, snap accelerate engine 5 times. Sensor should indicate a rich signal (.45 volt or more) at least once. If a rich signal is indicated at least once, go to step 4). If sensor does not display a rich signal at least once, go to next step.
  3. Check for open or short circuit in wiring harness between ECM and sensor No. 1. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair wiring as necessary. If wiring harness is okay, replace oxygen sensor and retest.
  4. Check all air induction components. Repair as necessary. If air induction components are okay, check fuel pressure. See BASIC TESTING article. Repair fuel pressure as necessary. If fuel pressure is okay, check fuel injectors. See SYSTEM/COMPONENT TESTS article. Replace injectors as necessary.
  5. If all injectors are okay, check Mass Airflow (MAF) sensor and Engine Coolant Temperature (ECT) sensor. See SYSTEM/COMPONENT TESTS article. Replace MAF and/or ECT sensor as necessary.
  6. If both components are okay, check ignition system. See IGNITION CHECKS in BASIC TESTING article. Repair ignition system as necessary. If ignition system is okay, check EVAP Vacuum Switching Valve (VSV). See SYSTEM/COMPONENT TESTS article. Replace EVAP VSV as necessary. If EVAP VSV is okay, replace ECM.
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