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Home › Mitsubishi › 2001 › Montero XLS › Repair and Diagnosis › Engine Performance › System › Engine Controls - Self-Diagnostics › Diagnostic Tests › P0125: Excessive Time To Enter Closed Loop Fuel Control › Diagnostic Procedure

Diagnostic Procedure

  1. Check for exhaust leaks. If exhaust leak exists, repair exhaust leak, then go to step  15. If exhaust leak does not exist, go to next step.
  2. Check for intake system vacuum leak. If vacuum leak exists, repair vacuum leak, then go to step  15. If vacuum leak does not exist, go to next step.
    NOTE: Manufacturer recommends connecting Test Harness Special Tool (MD998464) to right front HO2S and Test Harness Special Tool (MB991316) to left front HO2S. Connect jumper wires to appropriate test harness clips.
  3. Ensure engine is warmed up. Connect jumper wire between battery positive terminal and right front HO2S connector terminal No. 1 (component side). See Figure. Connect jumper wire between battery negative terminal and right front HO2S connector terminal No. 3 (component side). Connect digital voltmeter between right front HO2S connector terminals No. 2 and 4 (component side). Start engine. While repeatedly revving engine, measure right front HO2S output voltage. Voltage should be 0.6-1.0 volt. Repeat test with left front HO2S. If output voltage for each front HO2S is as specified, go to next step. If output voltage for either front HO2S is not as specified, replace appropriate front HO2S, then go to step  15.
  4. Check left front HO2S connector and right front HO2S connector for loose, damaged, or corroded terminals. If problem exists, repair connector(s), then go to step  15. If problem does not exist, go to next step.
  5. Disconnect left bank fuel injector connectors. On each left bank fuel injector, measure resistance between connector terminals (component side). Resistance should be 13-16 ohms at 68°F (20°C). If all resistances are as specified, go to next step. If any resistance is not as specified, replace faulty fuel injector, then go to step  15.
  6. Disconnect right bank fuel injector intermediate connector B-44. Measure resistance between following fuel injector intermediate connector terminals:
    • For fuel injector No. 1, measure between terminals No. 8 (Red wire) and No. 3 (Yellow/Blue wire).
    • For fuel injector No. 3, measure between terminals No. 8 (Red wire) and No. 1 (Light Green wire).
    • For fuel injector No. 5, measure between terminals No. 8 (Red wire) and No. 6 (Blue wire).

    See Figure. Resistance should be 13-16 ohms at 68°F (20°C). If all resistances are as specified, go to step  9. If any resistance is not as specified, go to next step.

  7. Remove intake manifold. Disconnect connector to right bank fuel injector that failed previous step. Measure resistance between fuel injector connector terminals (component side). 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 fuel injector, then go to step  15.
  8. Check connector to right bank fuel injector that failed step  6 for loose, damaged, or corroded terminals. If problem exists, repair connector, then go to step  15. If problem does not exist, repair wire between fuel injector connector and right bank fuel injector intermediate connector B-44, then go to step  15.
  9. Check right bank fuel injector intermediate connector B-44 for loose, damaged, or corroded terminals. If problem exists, repair connector, then go to step  15. If problem does not exist, go to next step.
  10. Check left bank fuel injector connectors for loose, damaged, or corroded terminals. If problem exists, repair appropriate connector(s), then go to step  15. If problem does not exist, go to next step.
  11. Check PCM connector D-107 for loose, damaged, or corroded terminals. If problem exists, repair connector, then go to step  15. If problem does not exist, go to next step.
  12. Check for damage to White wire between left front HO2S connector terminal No. 4 and PCM connector D-109 terminal No. 71. Check for damage to White wire between right front HO2S connector terminal No. 4 and PCM connector D-109 terminal No. 72. If problem exists, repair appropriate wire, then go to step  15. If problem does not exist, go to next step.
  13. Check for damage to wires between PCM and fuel injectors:
    • Check Yellow/Blue wire between fuel injector No. 1 connector terminal No. 2 and PCM connector D-107 terminal No. 1.
    • Check Yellow/Red wire between fuel injector No. 2 connector terminal No. 2 and PCM connector D-107 terminal No. 9.
    • Check Light Green wire between fuel injector No. 3 connector terminal No. 2 and PCM connector D-107 terminal No. 24.
    • Check Orange wire between fuel injector No. 4 connector terminal No. 2 and PCM connector D-107 terminal No. 2.
    • Check Blue wire between fuel injector No. 5 connector terminal No. 2 and PCM connector D-107 terminal No. 10.
    • Check White/Red wire between fuel injector No. 6 connector terminal No. 2 and PCM connector D-107 terminal No. 25.

    If problem exists, repair appropriate wire between fuel injector and PCM, then go to step  15. If problem does not exist, go to next step.

  14. Check fuel pressure. For procedure, see FUEL PRESSURE under FUEL SYSTEM in BASIC DIAGNOSTIC PROCEDURES article. At idle, fuel pressure should be about 38 psi (270 kPa) with fuel pressure regulator vacuum hose connected and 47-50 psi (330-350 kPa) with fuel pressure regulator vacuum hose disconnected. If fuel pressure is as specified, replace PCM, then go to next step. If fuel pressure is not as specified, repair fuel pressure problem, then go to next step.
  15. Test drive vehicle following OBD-II drive cycle other monitor pattern. See OTHER MONITOR  under OBD-II DRIVE CYCLES under VERIFYING REPAIRS. Check for DTCs. If DTC P0125 is output, retry diagnostic procedure. If DTC P0125 is not output, inspection is complete.
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