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Home >> Mazda >> 2003 >> Protege5 Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0125: Insufficient Coolant Temperature For Closed Loop Fuel Control >> Diagnostic Procedure

Diagnostic Procedure

  1. Verify Related Repair Information Availability -  Turn ignition off. Connect scan tool to DLC-2. Turn ignition on, engine off. Monitor for FREEZE FRAME DATA and ensure data has been recorded. Check service bulletins for repair information related to this DTC. If repair information is not available, go to next step. If repair information is available, perform diagnosis and repair as necessary. After repair, go to next step.
  2. Verify Current Input Signal Status - Is Concern Intermittent Or Constant -  Clear DTCs. See CLEARING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. Start engine and allow it to reach normal operating temperature. Using scan tool, access ECT PID data. If ECT PID is 96°F (35.6°C) or less, go to next step. If ECT PID is more than 96°F (35.6°C), problem is intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article.
  3. Inspect ECT Sensor Connector For Poor Connection -  Turn ignition off. Disconnect ECT sensor 2-pin harness connector. Check for poor connection due to damaged, pulled-out terminals, corrosion, etc. If terminals are okay, go to next step. If terminals are not okay, repair or replace as necessary. After repair, go to step  6.
  4. Inspect ECT Sensor -  Measure resistance between ECT sensor terminals. If resistance reading is about 2000 ohms, go to next step. If resistance reading is not about 2000 ohms, replace ECT sensor. After repair, go to step  6.
  5. Inspect PCM Connector For Poor Connection -  Disconnect PCM 104-pin harness connector. Check for poor connection due to damaged, pulled-out terminals, corrosion, etc. If no problem is found, go to next step. If any problem is found, repair as necessary and go to next step.
  6. Verify Trouble Shooting Of DTC P0125 Completed -  Reconnect all connectors. Turn ignition on, engine off. Clear DTCs. See CLEARING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. Ensure ECT PID is less than 68°F (20°C). Start engine and allow to reach normal operating temperature. Check for DTCs. See RETRIEVING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. If DTC P0125 is present, replace PCM. For PCM removal and installation, see POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in REMOVAL, OVERHAUL & INSTALLATION article. After repair, go to next step. If same DTC P0125 is not present, go to next step.
  7. Verify After Repair Procedure -  Using scan tool, perform After Repair Procedure. See AFTER REPAIR PROCEDURE . If no other DTCs are present, testing is complete. If any other DTC is present, follow appropriate DTC diagnostic procedure. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .
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