LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Suzuki >> 2002 >> XL-7 Base, RWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0125: Insufficient Coolant Temperature For Closed Loop Operation >> Diagnosis & Repair Procedure
April 5, 2026: LEMON Manuals is launched! Read the announcement.

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. Start engine and allow it to reach normal operating temperature. Using scan tool, select DATA LIST mode and observe ENGINE COOLANT TEMPERATURE parameter. If ENGINE COOLANT TEMPERATURE parameter is -40°F (-40°C), go to next step. If engine coolant temperature is not -40°F (-40°C), go to step  6.
  3. Turn ignition off. Disconnect ECT sensor 3-pin harness connector. ECT sensor is located at front of intake manifold. Use a fused jumper wire, connect ECT sensor harness connector terminals No. 1 (Orange/Black wire) and No. 3 (Gray/Yellow wire). Turn ignition on. Observe ENGINE COOLANT TEMPERATURE parameter displayed on scan tool. If parameter is 327°F (164°C), go to step  5. If parameter is not as specified, check for open or short in Orange/Black wire between ECT sensor and ECM. See WIRING DIAGRAMS article. Also, check for open or short in and Gray/Yellow wire between ECT sensor and ECM. If problem is found, repair as necessary. After repair, repeat DTC CONFIRMATION TEST . If no problem is found, go to next step.
  4. Substitute a known good ECM, and repeat DTC CONFIRMATION TEST . If DTC does not reset, testing is complete.
  5. Check ECT sensor operation. See ENGINE COOLANT TEMPERATURE SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article. If problem is found, replace as necessary. After repair, repeat DTC CONFIRMATION TEST . If no problem is found, go to next step.
  6. Check thermostat operation. Thermostat should begin to open at 175.4-182.6°F (79.7-83.7°C). Thermostat should be completely open at 203°F (95°C). Thermostat valve should lift to more than 51/64" (8 mm). If problem is found, replace thermostat as necessary. After repair, repeat DTC CONFIRMATION TEST . If no problem is found, go to next step.
  7. Substitute a known good ECM, and repeat DTC CONFIRMATION TEST . If DTC does not reset, testing is complete.
scientia non olet · About LEMON Manuals