P0125

2AR-FE ENGINE CONTROL: SFI SYSTEM: P0125: Insufficient Coolant Temperature for Closed Loop Fuel Control
P0125 - Insufficient Coolant Temperature for Closed Loop Fuel Control

DESCRIPTION

- Refer to DTC P0115 P0115.





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 output voltage signal of the sensor. The output voltage signal varies according to the changing resistance of the sensor. After the engine is started, the engine coolant temperature is monitored through 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:

The engine coolant temperature is 0°C (32°F) at engine start. After approximately 1 minute 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





TYPICAL ENABLING CONDITIONS





TYPICAL MALFUNCTION THRESHOLDS





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 / Data List / 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 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 / Trouble Codes.

12. Read the pending DTCs.

HINT
- If a pending DTC is output, the system is malfunctioning.
- If a pending DTC is not output, perform the following procedure.

13. Enter the following menus: Powertrain / Engine / Utility / All Readiness.

14. Input the DTC: P0125.

15. Check the DTC judgment result.





HINT
- If the judgment result shows NORMAL, the system is normal.
- If the judgment result shows ABNORMAL, the system has a malfunction.

16. If the judgment result is INCOMPLETE or UNKNOWN and no pending DTC is output, perform a universal trip and check for permanent DTCs DTC Check / Clear.

HINT
- If a permanent DTC is output, the system is malfunctioning.
- If no permanent DTC is output, the system is normal.

WIRING DIAGRAM

Refer to DTC P0115 P0115.

INSPECTION PROCEDURE

HINT
- If DTC P0115, P0116, P0117 or P0118 is stored simultaneously with DTC P0125, the engine coolant temperature sensor may have an open or short circuit. Troubleshoot those DTCs first.
- Read freeze frame data using the Techstream. Freeze frame data records the engine condition when malfunctions are detected. 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.

PROCEDURE

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

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / Engine / Trouble Codes.

(e) Read the DTCs.

Result





HINT
If any DTCs other than P0125 are output, troubleshoot those DTCs first.

B -- GO TO DTC CHART Engine Control - SFI System
A -- Continue to next step.

2. INSPECT THERMOSTAT

(a) Remove the thermostat Removal.

(b) Check the valve opening temperature of the thermostat.

Standard opening temperature:

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.

NG -- REPLACE THERMOSTAT Removal
OK -- Continue to next step.

3. CHECK COOLING SYSTEM

(a) 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 Removal