Dtc P0125 Insufficient Coolant Temperature For Closed Loop Fuel Control

Engine Hybrid System. Yaris. Ncp93, 131
1Nz-Fe Engine Control. Yaris. Ncp93, 131

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

  1. Refer to DTC P0115 (YARIS_NCP93 RM000000PF50KSX_01.html).

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

MONITOR DESCRIPTION

The resistance of the ECT sensor varies in proportion to the actual ECT. The ECT supplies a constant voltage to the sensor and monitors the signal output voltage of the sensor. The signal voltage output varies according to the changing resistance of the sensor. After the engine is started, the ECT is monitored through this signal. If the ECT 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:
The ECT is 0°C (32°F) at engine start. After about 1 minute of running time, the ECT 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
Required Sensors/Components (Main)
Thermostat, cooling system
Required Sensors/Components (Related)
Engine coolant temperature sensor and mass air flow meter
Frequency of Operation
Once per driving cycle
Duration
62 seconds: Engine coolant temperature at engine start -3.3°C (26°F) or more
112 seconds: Engine coolant temperature at engine start -14.44° to -3.3°C (6.0° to 26°F)
20 minutes: Engine coolant temperature at engine start less than -14.44°C (6.0°F)
MIL Operation
2 driving cycles
Sequence of Operation
None

TYPICAL ENABLING CONDITIONS


Monitor runs whenever following DTCs not present
None
Thermostat fail (P0128)
Not detected
IAT sensor fail (P0110, P0112, P0113)
Not detected
ECT sensor fail (P0115, P0117, P0118)
Not detected
MAF sensor fail (P0100, P0101, P0102, P0103)
Not detected

TYPICAL MALFUNCTION THRESHOLDS


Time until actual engine coolant temperature reaches closed-loop fuel control enabling temperature
62 seconds: Engine coolant temperature at engine start -3.3°C (26°F) or more
112 seconds: Engine coolant temperature at engine start -14.44° to -3.3°C (6.0° to 26°F)
20 minutes: Engine coolant temperature at engine start less than -14.44°C (6.0°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 menu items: Powertrain / Engine and ECT / Data List / Coolant Temp.
  5. Check that the engine coolant temperature is 10°C (50°F) or less.
  6. Clear DTCs (even if no DTCs are stored, perform the clear DTC operation).
  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 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 test result is INCOMPLETE or N/A and no pending DTC is output, perform a universal trip and check for permanent DTCs (YARIS_NCP93 RM000000PDK0QGX.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 (YARIS_NCP93 RM000000PF50KSX_07.html).

INSPECTION PROCEDURE

HINT:
  1. If any of DTCs P0115, P0116, P0117 or P0118 are stored simultaneously with DTC P0125, the Engine Coolant Temperature (ECT) 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 help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air fuel ratio was lean or rich, and other data from the time the malfunction occurred.
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
    Display (DTC Output)
    		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 (YARIS_NCP93 RM000000PDF0E6X.html)
A


2.INSPECT THERMOSTAT

  1. Remove the thermostat (YARIS_NCP93 RM000001DGA00ZX.html).

  1. Check the valve opening temperature of the thermostat.

    Standard Value:
    80°C to 84°C (176°F 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 (YARIS_NCP93 RM000001DG700ZX.html).



NG
REPLACE THERMOSTAT (YARIS_NCP93 RM000001DGA00ZX.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 (YARIS_NCP93 RM000001DBH011X.html)