Mike's Workshop Manuals: Service manuals for every vehicle
Home >> Mazda >> 2003 >> MX-5 Miata Base, 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. See Figure. 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 step  6.
  2. Verify Current Input Signal Status - Is Concern Intermittent Or Constant -  Start engine and let idle until normal operating temperature is reached. Using scan tool, monitor ECT PID. If ECT PID reading is less than 140°F (60°C), go to next step. If ECT PID reading is more than 140°F (60°C), problem is intermittent. See INTERMITTENTS in TROUBLESHOOTING - NO CODES article.
  3. Inspect ECT Sensor Connector For Poor Connection -  Turn ignition off. Disconnect ECT sensor 3-pin harness connector. See Figure. Check ECTsensor for poor connection due to damaged, pulled-out pins, corrosion, etc. If connector terminals are okay, go to next step. If connector terminals are found faulty, repair or replace as necessary. After repair, go to step  6.
  4. Inspect ECT Sensor -  Measure resistance between ECT sensor 3-pin connector terminals "A" and "B". Resistance reading should be 2270-2740 ohms at 68°F (20°C). If resistance reading is as specified, go to next step. If resistance reading is not as specified, replace ECT sensor. After repair, go to step  6.
  5. Inspect PCM Connector For Poor Connection -  Disconnect PCM 31-pin harness connector. See Figure. Check PCM 31-pin harness connector terminals "4P" and "4O" for poor connection due to damaged, pulled-out pins, corrosion, etc. If connector terminals are okay, go to next step. If connector terminals are found faulty, repair or replace as necessary. After repair, go to next step.
  6. Verify Troubleshooting Of DTC P0125 Completed -  Return vehicle to original condition. Using scan tool, clear DTCs from PCM memory. See CLEARING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. Access ECT PID and wait until ECT PID is less than 68°F (20°C). Start engine and let idle until normal operating temperature is reached. Monitor for pending DTCs. If same DTC is not present, go to next step. If same 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.
  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 .
scientia non olet · About Mike's Workshop Manuals