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Home >> Lexus >> 1997 >> ES 300 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Circuit Tests >> DTC P0125 - Insufficient Coolant Temperature For Closed Loop Fuel Control >> Diagnosis & Repair

Diagnosis & Repair

  1. Connect scan tool to Data Link Connector (DLC) No. 3. See Figure. Start engine and warm to normal operating temperature. Using scan tool, monitor each oxygen sensor. Snap accelerate engine 3 times. Sensors should indicate a rich signal (.45 volt or more) at least once.
  2. If a rich signal is indicated for both sensors, replace ECM and retest system. If either sensor does not display a rich signal, check for open or short circuit in wiring harness between ECM and suspect sensor. Repair as necessary. If wiring harness is okay, replace oxygen sensor and retest system.
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