LEMON Manuals: Even more car manuals for everyone
Home >> Toyota >> 2001 >> Sienna CE >> Repair and Diagnosis >> External Pages >> Different car >> Section 38 (Engine Controls - Self-Diagnostics) >> Diagnostic Tests >> DTC P0125: Insufficient Coolant Temperature For Closed Loop Fuel Control >> Diagnosis & Repair

Diagnosis & Repair

WARNING: This page is about a different car, the 2002 Lexus ES 300. 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. See Figure. 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 OUTPUT VOLTAGE SPECIFICATIONS  table. If voltage is as specified, go to next step. If voltage is not as specified, go to step  10.
    AIR/FUEL RATIO SENSOR OUTPUT VOLTAGE SPECIFICATIONS

    Application & Operating Condition Specification
    Using OBD-II Scan Tool
    Engine Idling, Engine Racing & Driving Vehicle (1) (2)
    Using Toyota Hand-Held Tester
    Engine Idling, Engine Racing & Driving Vehicle (1) (3)
    (1) Drive vehicle at 25 MPH or more with engine speed of 1500 RPM or more while opening and closing the throttle.
    (2) Voltage should not remain at .56 volt or less, .66 volt, or .76 volt or more.
    (3) Voltage should not remain at 2.80 volts or less, 3.30 volts, or 3.80 volts or more.
  3. Check connection of PCV hose. Repair or replace hose as necessary. If hose is okay, go to next step.
  4. Check harness and connectors between ECM and A/F sensor. See WIRING DIAGRAMS article. Repair harness and connectors as necessary. If harness and connectors are okay, go to next step.
  5. Disconnect suspect A/F sensor harness connector. Measure resistance between terminal B+ (Black wire on bank No. 1; Black/White wire on bank No. 2) and HT (Black/White wire on bank No. 1; Black/Red wire on bank No. 2) at A/F sensor connector (component side). See Fig 1. Resistance should be 2.16-2.88 ohms at 68°F (20°C). If resistance is not as specified, replace appropriate A/F sensor. If resistance is not as specified, go to next step.
  6. Ensure oil dipstick, oil filler cap 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.
  7. Check fuel pressure. See FUEL SYSTEM in BASIC DIAGNOSTIC PROCEDURES article. If fuel pressure is not to specification, repair as necessary. If fuel pressure is to specification, go to next step.
  8. Check fuel injectors. See FUEL SYSTEM in SYSTEM & COMPONENT TESTING - ES300 & RX300 article. If problem exists, repair as necessary. If problem does not exist, go to next step.
  9. Check exhaust system for leaks. If problem exists, repair as necessary. If problem does not exist, replace defective A/F sensor(s).
  10. Clear DTCs. Perform test drive confirmation, then go to next step. See TEST DRIVE CONFIRMATION  under DTC P1130 OR DTC P1150: AIR/FUEL SENSOR CIRCUIT RANGE/PERFORMANCE.
  11. Recheck for DTCs. If DTC P0125 is displayed again, replace ECM. If DTC P0125 is not displayed again, go to next step.
  12. Vehicle either ran out of fuel or problem is intermittent. Check component and ECM connections.
Fig 1: Testing A/F Sensor & Heated Oxygen Sensor No. 1 Heater
G98E11506Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
scientia non olet · About LEMON Manuals