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Home >> Toyota >> 2002 >> RAV4 Base, AWD, Automatic >> Repair and Diagnosis >> External Pages >> Different car >> Section 11 (Engine Control System Self-Diagnostics) >> Diagnostic Tests >> DTC P0125: Insufficient Coolant Temperature For Closed Loop Fuel Control >> Diagnosis & Repair
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Diagnosis & Repair

WARNING: This page is about a different car, the 2002 Toyota MR2. However, it is still accessible from the selected car via links, so may be relevant.
  1. Using Toyota hand-held tester or scan tool, check for any other DTCs. If only DTC P0125 is displayed, go to next step. If any other DTCs are displayed, diagnose and repair those DTCs first and retest.
  2. Connect hand-held tester or scan tool to Data Link Connector (DLC) No. 3. See Figure. Start and warm engine to normal operating temperature. Using hand-held tester or scan tool, monitor heated oxygen sensor No. 1 (bank No. 1 sensor No. 1 or bank No. 2 sensor No. 1) voltage. Snap accelerate engine to about 4000 RPM 3 times. Heated oxygen sensor No. 1 should indicate a rich signal (.45 volt or more) at least once. If heated oxygen sensor No. 1 does not display a rich signal at least once, go to next step. If a rich signal is indicated for heated oxygen sensor No. 1 at least once, go to step  9.
  3. Check for open or short in wiring between appropriate heated oxygen sensor No. 1 and ECM. If problem does not exist, go to next step. If problem exists, repair wiring as necessary. See WIRING DIAGRAMS article.
  4. Using hand-held tester or scan tool, check if a misfire has occurred by monitoring DTCs and DATA LIST. If misfire has not occurred, go to next step. If misfire has occurred, perform DTC P0300: RANDOM MISFIRE DETECTED .
  5. Ensure oil dipstick, oil filler cap, PCV system and all other air induction system components are intact and operating properly. If problem does not exist, go to next step. If problem exists, repair as necessary.
  6. Check fuel pressure. See FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4-CYLINDER article. Fuel pressure should be 44-50 psi (3.1-3.5 kg/cm2 ) at idle, and should be 21 psi (1.5 kg/cm2 ) or more for 5 minutes after engine has stopped. If fuel pressure is as specified, go to next step. If fuel pressure is not as specified, repair as necessary.
  7. Check operation of fuel injectors. See FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 4-CYLINDER article. Fuel injector volume should be .16-.20 oz. (47-58 cc) every 15 seconds and difference in volume between each fuel injector should be less than .03 oz. (10 cc). Fuel injector should not leak more than one drop every 12 minutes. If problem does not exist, go to next step. If problem exists, repair as necessary.
  8. Check exhaust system for leaks. If problem exists, repair as necessary. If problem does not exist, replace defective heated oxygen sensor No. 1.
  9. Clear DTCs. Perform test drive confirmation, then go to next step. See TEST DRIVE CONFIRMATION  under DTC P0130 OR P0150: HEATED OXYGEN SENSOR NO. 1 CIRCUIT.
  10. Recheck for DTCs. If DTC P0125 is displayed again, replace ECM. If DTC P0125 is not displayed again, go to next step.
  11. Vehicle either ran out of fuel or problem is intermittent. Check component and ECM connections.
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