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Home >> Saturn >> 2003 >> LW200 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0125: ECT Excessive Time To Enter Closed Loop >> Diagnostic Procedures
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Diagnostic Procedures

  1. Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM.
    2. NOTE: The cooling fans are commanded ON when certain ECT DTCs are set.
  2. Is the cooling system coolant low? If yes, diagnose cause of coolant loss. Repair as necessary. If no, go to next step.
  3. Test and verify the proper operation of the thermostat. Did you find and correct the condition? If yes, go to step  14. If no, go to next step.
  4. Disconnect the ECT sensor. Inspect for corrosion on the ECT sensor terminals, improper or corroded terminals at the ECT harness connector, or loose terminals in the ECT harness connector. Did you find and correct the condition? If yes, go to step  14. If no, go to next step.
  5. Measure the voltage from the signal circuit of the ECT sensor to a good ground with a DVOM. Is the voltage within 4.8-5.2 volts? If yes, go to next step. If no, go to step  8.
  6. Measure the voltage from the signal circuit of the ECT sensor to the low reference circuit of the ECT sensor with a DVOM. Is the voltage within 4.8-5.2 volts? If yes, go to step  9. If no, go to next step.
  7. Test the ECT sensor low reference circuit for high resistance. Did you find and correct the condition? If yes, go to step  14. If no, go to step  11.
  8. Test the ECT sensor signal circuit for high resistance. Did you find and correct the condition? If yes, go to step  14. If no, go to step  11.
  9. Turn ignition off. Remove the ECT sensor. Place the sensor on a work surface away from any heat source. Allow the sensor to reach the ambient air temperature for 30-60 minutes. Observe and record the ambient air temperature of the vehicle environment using an accurate thermometer. Measure the resistance of the ECT sensor and record the value. Compare the resistance measurement of the ECT sensor to the ambient air temperature on the Temperature vs. Resistance table. Refer to TEMPERATURE VS RESISTANCE in SENSOR OPERATING RANGE CHARTS - CARS article. Is the resistance measurement of the ECT sensor within the specified range? If yes, go to next step. If no, go to step  12.
  10. Install ECT sensor. After reinstalling sensor, see INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 2.2L SATURN "L" SERIES article.
  11. Test for an intermittent and for a poor connection at the PCM. Did you find and correct the condition? If yes, go to step  14. If no, go to step  13.
  12. Replace ECT sensor. After replacement, go to step  14.
  13. Replace PCM. See POWERTRAIN CONTROL MODULE in REMOVAL & INSTALLATION - SATURN "L" SERIES article. Perform PCM relearn procedure. See PCM REPROGRAMMING  under PROGRAMMING. After replacing PCM, go to next step.
  14. Clear the DTCs with a scan tool. Turn ignition off for 90 seconds. Start the engine. Operate the vehicle within the Conditions for Running the DTC. See CONDITIONS FOR RUNNING DTC . You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition? If yes, go to step  2. If no, go to next step.
  15. Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? If yes, go to DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
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