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Home >> Toyota >> 2000 >> RAV4 Base, AWD, Automatic >> Repair and Diagnosis >> External Pages >> Different car >> Section 1 (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 2000 Toyota Avalon. However, it is still accessible from the selected car via links, so may be relevant.
  1. If other DTCs are displayed, diagnose and repair those DTCs first and retest system. If only DTC P0125 is displayed, go to next step.
  2. Connect scan tool to Data Link Connector (DLC) No. 3. Start engine and increase engine speed to 2500 RPM for approximately 90 seconds. Using scan tool, monitor each A/F sensor output voltage. See AIR/FUEL RATIO SENSOR VOLTAGE SPECIFICATIONS  table. If voltage is as specified, go to next step. If voltage is not as specified, go to step  9.
    AIR/FUEL RATIO SENSOR VOLTAGE SPECIFICATIONS

    Application (1) Volts
    Using OBD-II Scan Tool
    Engine Idling 0.66
    Engine Racing 0.76 Or More
    Driving Vehicle (2) 0.56 Or Less
    Using Toyota Hand-Held Tester
    Engine Idling 3.3
    Engine Racing 3.8 Or More
    Driving Vehicle (2) 2.8 Or Less
    (1) Voltage should not remain constant at specification given.
    (2) Drive vehicle at 25 MPH or more, with engine speed at 1500 RPM or more, while opening and closing throttle valve.
  3. Check for open or short in wiring between ECM and suspect A/F sensor. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, go to next step.
  4. Disconnect suspect A/F sensor harness connector. A/F sensor for bank 2 is located in exhaust manifold. A/F sensor for bank 1 is located in exhaust pipe in front of catalytic converter. Measure resistance between terminals B+ (Black/White wire) and HT (Black/Red wire) at A/F sensor connector (component side). See Fig 1. Resistance should be .8-1.4 ohms at 68°F (20°C) and 1.8-3.2 ohms at 1472°F (800°C). If resistances are not as specified, replace appropriate A/F sensor. If resistances are as specified, go to next step.
  5. Ensure oil dipstick, oil filler cap, PCV system and all other air induction system components are intact and operating properly. If problem exists, repair as necessary. If problem does not exist, go to next step.
  6. Check fuel pressure. See FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If fuel pressure is not within specification, repair as necessary. If fuel pressure is within specification, go to next step.
  7. Check fuel injectors. See FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - V6 & V8 article. If problem exists, repair as necessary. If problem does not exist, go to next step.
  8. Check exhaust system for leaks. If problem exists, repair as necessary. If problem does not exist, replace defective A/F sensor.
  9. Perform test drive confirmation, then go to next step. See TEST DRIVE CONFIRMATION  under DTC P1130 OR P1150: AIR/FUEL SENSOR CIRCUIT RANGE/PERFORMANCE.
  10. Clear and 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.
Fig 1: Testing A/F Sensor Heater
G00009723Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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