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Home >> Pontiac >> 2001 >> Firebird Formula, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics - 5.7L >> Diagnostic Tests >> DTC P0125: Engine Coolant Temperature Excessive Time To Enter Closed Loop Fuel Control >> Diagnostic Procedures

Diagnostic Procedures

  1. If powertrain diagnostic system check was performed, go to next step. If powertrain diagnostic system check was not performed, go to POWERTRAIN DIAGNOSTIC SYSTEM CHECK  under DIAGNOSTIC SYSTEM TESTS. After performing powertrain diagnostic system check, go to next step.
  2. Check coolant level. If coolant level is low, fill coolant to proper level. Check for additional DTCs. If any additional DTCs are set, go to applicable DTC test. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no additional DTCs are set, go to next step.
  3. Turn ignition off. Locate and disconnect ECT sensor. See Figure. Connect a fused jumper wire between ECT sensor connector terminals. Turn ignition on. Monitor ECT sensor temperature on scan tool. If scan tool indicates ECT value is more than 280°F (138°C), go to step  7. If scan tool indicates ECT value less than 280°F (138°C), go to next step.
  4. Turn ignition off. Connect a fused jumper wire between ECT sensor connector terminal "B" (Yellow wire) and ground. Turn ignition on. Monitor ECT sensor temperature on scan tool. If scan tool indicates ECT value is more than 280°F (138°C), go to next step. If scan tool indicates ECT value less than 280°F (138°C), go to step  6.
  5. Repair open or high resistance in Black wire between ECT sensor connector terminal "A" and PCM connector C1 terminal No. 80. See Figure. After repairs, go to step  10.
  6. Repair open or high resistance in Yellow wire between ECT sensor connector terminal "B" and PCM connector C1 terminal No. 74. See Figure. After repairs, go to step  10.
  7. Remove ECT sensor. Using a pan of hot water, check ECT sensor temperature/resistance. See appropriate SENSOR OPERATING RANGE CHARTS article. If ECT sensor is closely matches sensor operating range chart, go to next step. If ECT sensor does not closely match sensor operating range chart, go to step  9.
  8. Reinstall ECT sensor and diagnose thermostat. See appropriate article in ENGINE COOLING.
  9. Replace ECT sensor. See REMOVAL, OVERHAUL & INSTALLATION - CARS article. After replacing sensor, go to next step.
  10. Using scan tool, clear DTCs. Turn ignition off for at least 30 seconds. Start engine and allow it to reach normal operating temperature. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, go to step  2.
  11. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no undiagnosed DTCs are displayed, system is okay.
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