Dtc P0125 Insufficient Coolant Temperature For Closed Loop Fuel Control

Engine Hybrid System. Corolla. Zre142 Aze141
2Az-Fe Engine Control. Corolla. Zre142 Aze141

DESCRIPTION

MONITOR DESCRIPTION

MONITOR STRATEGY

TYPICAL ENABLING CONDITIONS

TYPICAL MALFUNCTION THRESHOLDS

CONFIRMATION DRIVING PATTERN

WIRING DIAGRAM

INSPECTION PROCEDURE

CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0125)

INSPECT THERMOSTAT

CHECK COOLING SYSTEM

DTC P0125 Insufficient Coolant Temperature for Closed Loop Fuel Control


DESCRIPTION

Refer to DTC P0115 (Link).

DTC No.
DTC Detection Condition
Trouble Area
P0125
Engine coolant temperature does not reach closed-loop enabling temperature for 20 minutes (this period varies with engine start engine coolant temperature)
(2 trip detection logic)
  1. Cooling system
  2. Engine coolant temperature sensor
  3. Thermostat

MONITOR DESCRIPTION

The resistance of the engine coolant temperature sensor varies in proportion to the actual engine coolant temperature. The ECM supplies a constant voltage to the sensor and monitors the signal output voltage of the sensor. The signal output voltage varies according to the changing resistance of the sensor. After the engine is started, the engine coolant temperature is monitored by this signal. If the engine coolant temperature sensor indicates that the engine is not yet warm enough for closed loop fuel control, despite a specified period of time having elapsed since the engine was started, the ECM interprets this as a malfunction in the sensor or cooling system and stores the DTC.
Example:
When the engine coolant temperature is 10°C (50°F) at engine start: After approximately 52 seconds of running time, the engine coolant temperature sensor still indicates that the engine is not warm enough to begin closed loop fuel (air fuel ratio feedback) control. The ECM interprets this as a malfunction in the sensor or cooling system and stores the DTC.

MONITOR STRATEGY


Related DTCs
P0125: Insufficient engine coolant temperature for closed-loop fuel control rationality
Required Sensors/Components (Main)
Engine coolant temperature sensor
Thermostat
Cooling system
Required Sensors/Components (Related)
-
Frequency of Operation
Once per driving cycle
Duration
52 seconds: Engine coolant temperature at engine start 1.67°C (35°F) or more
111 seconds: Engine coolant temperature at engine start -9.44°C (15°F) or more, and less than 1.67°C (35°F)
1200 seconds: Engine coolant temperature at engine start less than -9.44°C (15°F)
MIL Operation
2 driving cycles
Sequence of Operation
None

TYPICAL ENABLING CONDITIONS


Monitor runs whenever following DTCs are not present
None
Thermostat fail (P0128)
Not detected
Intake air temperature sensor fail (P0112, P0113)
Not detected
Engine coolant temperature sensor fail (P0115, P0117, P0118)
Not detected
Mass air flow meter fail (P0101, P0102, P0103)
Not detected

TYPICAL MALFUNCTION THRESHOLDS


Time until actual engine coolant temperature reaches closed-loop fuel control enabling temperature
52 seconds: Engine coolant temperature at engine start 1.67°C (35°F) or more
111 seconds: Engine coolant temperature at engine start -9.44°C (15°F) or more, and less than 1.67°C (35°F)
1200 seconds: Engine coolant temperature at engine start less than -9.44°C (15°F)

CONFIRMATION DRIVING PATTERN

  1. Leave the vehicle outside overnight.
  2. Connect the Techstream to the DLC3.
  3. Turn the ignition switch to ON and turn the Techstream on.
  4. Enter the following menus: Powertrain / Engine and ECT / Data List / Primary / Coolant Temp.
  5. Check that the engine coolant temperature is 10°C (50°F) or less.
  6. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).
  7. Turn the ignition switch off and wait for at least 30 seconds.
  8. Turn the ignition switch to ON and turn the Techstream on.
  9. Start the engine.
  10. Wait 21 minutes or more.
  11. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
  12. Read the pending DTCs.
    HINT:
    1. If a pending DTC is output, the system is malfunctioning.
    2. If a pending DTC is not output, perform the following procedure.
  13. Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
  14. Input the DTC: P0125.
  15. Check the DTC judgment result.

    Techstream Display
    		Description
    NORMAL
    1. DTC judgment completed
    2. System normal
    ABNORMAL
    1. DTC judgment completed
    2. System abnormal
    INCOMPLETE
    1. DTC judgment not completed
    2. Perform driving pattern after confirming DTC enabling conditions
    N/A
    1. Unable to perform DTC judgment
    2. Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit
    HINT:
    1. If the judgment result shows NORMAL, the system is normal.
    2. If the judgment result shows ABNORMAL, the system has a malfunction.
  16. If the judgment result is INCOMPLETE or N/A and no pending DTC is output, perform a universal trip and check for permanent DTCs (COROLLA_ZRE142 RM000000PDK0ZBX.html).
    HINT:
    1. If a permanent DTC is output, the system is malfunctioning.
    2. If no permanent DTC is output, the system is normal.

WIRING DIAGRAM

Refer to DTC P0115 (COROLLA_ZRE142 RM000000PF50QLX_07.html).

INSPECTION PROCEDURE

HINT:
  1. If any of DTCs P0115, P0117 or P0118 are set simultaneously with DTC P0125, the engine coolant temperature sensor may have an open or a short circuit. Troubleshoot those DTCs first.
  2. Read freeze frame data using the Techstream. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.
1.CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0125)

  1. Connect the Techstream to the DLC3.

  1. Turn the ignition switch to ON.

  1. Turn the Techstream on.

  1. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

  1. Read DTCs.

    Result:

    Result
    		Proceed to
    P0125
    		A
    P0125 and other DTCs
    		B
    HINT:
    If any DTCs other than P0125 are output, troubleshoot those DTCs first.


B
GO TO DTC CHART (COROLLA_ZRE142 RM000000PDF0G9X.html)
A


2.INSPECT THERMOSTAT

  1. Remove the thermostat (COROLLA_ZRE142 RM0000017WE03UX.html).

  1. Check the valve opening temperature of the thermostat.

    Standard Value:
    80 to 84°C (176 to 183°F)
    HINT:
    In addition to the above check, confirm that the valve is completely closed when the temperature is below the standard.

  1. Reinstall the thermostat (COROLLA_ZRE142 RM0000017WB03UX.html).



NG
REPLACE THERMOSTAT (COROLLA_ZRE142 RM000001X9702FX.html)
OK


3.CHECK COOLING SYSTEM

  1. Check for defects in the cooling system that might cause the system to be too cold, such as abnormal radiator fan operation or any modifications.



NG
REPAIR OR REPLACE COOLING SYSTEM
OK

REPLACE ENGINE COOLANT TEMPERATURE SENSOR (COROLLA_ZRE142 RM0000017U803CX.html)