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Home › Mitsubishi › 2000 › Diamante LS › Repair and Diagnosis › Engine Performance › System › Engine Controls - Self-Diagnostics › Diagnostic Tests › DTC P0125: Excessive Time To Enter Closed Loop Fuel Control › Diagnostic Procedure

Diagnostic Procedure

  1. Disconnect front Heated Oxygen Sensor (HO2S) connector. Connect Test Harness (MD991223 on Federal vehicles; MD998464 on California vehicles) to front HO2S. Check resistance (at room temperature) between test harness terminals No. 3 and 4 (Federal vehicle), or terminals No. 1 and 3 (California vehicle). Resistance should be 7-40 ohms on Federal vehicle, or 4.5-8 ohms on California vehicle. If resistance is as specified, go to next step. If resistance is not as specified, replace front HO2S.
  2. Start and warm engine until engine coolant temperature is 176°F (80°C) or more. On Federal vehicle, connect jumper wires between battery positive terminal and test harness terminal No. 3, and between battery negative terminal and test harness terminal No. 4. Connect DVOM between test harness terminals No. 1 and 2. On California vehicle, connect jumper wires between battery positive terminal and test harness terminal No. 1, and between battery negative terminal and test harness terminal No. 3. Connect DVOM between test harness terminals No. 2 and 4. On all vehicles, check front HO2S output voltage while repeatedly racing engine. If voltage is 600-1000 millivolts, go to next step. If voltage is not 600-1000 millivolts, replace front HO2S.
  3. Turn ignition off. Check connectors and wiring between front HO2S and PCM. If problem exists, repair connectors or wiring as necessary. If problem does not exist, go to next step.
  4. Disconnect fuel injector connectors. Check resistance between fuel injector terminals. Resistance should be 13-16 ohms at 68°F (20°C). If resistance is as specified, go to next step. If resistance is not as specified, replace appropriate fuel injector.
  5. Connect fuel injector connectors. Using stethoscope, check fuel injector operating sound during cranking or at idle. Ensure frequency of operating sound increases as engine RPM increases. If operating sound is heard from all fuel injectors, go to next step. If no operating sound is heard from a fuel injector, check fuel injector drive circuit. See DTC P0201-P0206: INJECTOR NO. 1-6 CIRCUIT MALFUNCTION  .
  6. Check fuel injector connectors and wiring between PCM and fuel injectors. If problem exists, repair as necessary. If problem does not exist, go to next step.
  7. Perform fuel pressure test. See FUEL SYSTEM in BASIC DIAGNOSTIC PROCEDURES article. If fuel pressure is not okay, repair as necessary. If fuel pressure is okay, go to next step.
  8. Check for leaks in air intake or exhaust system. Check for exhaust leaks at HO2S fittings, exhaust manifold or front pipes. Check for fuel filter and/or fuel line blockage. Check fuel pump for poor fuel supply. If problem exists, repair as necessary. If problem does not exist, replace PCM.
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