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Home >> Suzuki >> 2002 >> Esteem GL, 4D Sedan, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics - 1.8L >> Diagnostic Tests >> DTC P0125: Insufficient Coolant Temperature For Closed Loop Operation >> Diagnosis & Repair Procedure
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Diagnosis & Repair Procedure

  1. If engine system check has been performed, go to next step. If engine system check has not been performed, go to A4: ENGINE SYSTEM CHECK  under SYSTEM TESTS.
  2. Turn ignition off. Start engine and allow it to reach normal operating temperature. Using scan tool, check ENGINE COOLANT TEMPERATURE parameter. If parameter is less than 88°F (31°C), go to next step. If parameter is 88°F (31°C) or more, go to step  7 .
  3. Turn ignition off. Disconnect ECT sensor No. 2 3-pin harness connector. ECT sensor is located in thermostat housing. See Figure . Connect a fused jumper wire between ECT sensor No. 2 harness connector terminal No. 1 (Light Green/Red wire) and No. 3 (Orange wire). Turn ignition on. On scan tool, check ENGINE COOLANT TEMPERATURE parameter. If parameter is 401°F (205°C), go to step  6 . If parameter is not 401°F (205°C), go to next step.
  4. Check for short or open in Light Green/Red and Orange wires between ECT sensor No. 2 and ECM harness connector C20. See WIRING DIAGRAMS article. If problem is found, repair as necessary. After repair, repeat DTC CONFIRMATION TEST  . If no problem is found, go to next step.
  5. Substitute a known good ECM, and repeat DTC CONFIRMATION TEST  . If DTC does not reset, testing is complete.
  6. Drain coolant. Remove ECT sensor from thermostat housing and place in water with a thermometer. Heat water to specified temperature and check resistance. See Figure . If sensor resistance is as specified, go to next step. If sensor resistance is not as specified, replace ECT sensor. After repair, repeat DTC CONFIRMATION TEST  .
  7. Check thermostat operation. If heater takes a long time to warm up, or coolant flows into radiator on cold start, remove thermostat for inspection. If problem is found, replace thermostat as necessary. After repair, repeat DTC CONFIRMATION TEST  . If thermostat operates properly, go to next step.
  8. Substitute a known good ECM, and repeat DTC CONFIRMATION TEST  . If DTC does not reset, testing is complete.
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