Mike's Workshop Manuals: Service manuals for every vehicle
Home >> Toyota >> 2001 >> Land Cruiser >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics >> Diagnostic Tests >> DTC P0125: Insufficient Coolant Temperature For Closed Loop Fuel Control >> Diagnosis & Repair

Diagnosis & Repair

  1. If any other DTCs are displayed, diagnose and repair those DTCs first and retest. If only DTC P0125 is displayed, go to next step.
  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 each heated oxygen sensor No. 1 output voltage. Snap accelerate engine to about 4000 RPM 3 times. Both heated oxygen sensors No. 1 should indicate a rich signal (.45 volt or more) at least once. If either 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 both heated oxygen sensors No. 1 at least once, go to step  9.
  3. Check for open or short in wiring between appropriate heated oxygen sensor(s) 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 a 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 - V6 & V8 article. Fuel pressure should be 38-44 psi (2.7-3.1 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 - V6 & V8 article. Fuel injector volume should be 3.4-4.2 Cu. In. (56-69 cc) every 15 seconds and difference in volume between each fuel injector should be less than .8 Cu. In. (13 cc). Fuel injectors 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(s) 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 not displayed again, go to next step. If DTC P0125 is displayed again, replace ECM.
  11. Vehicle either ran out of fuel or problem is intermittent. Check component and ECM connections.
scientia non olet · About Mike's Workshop Manuals