Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Inspection Procedure
HINT:
- If any of DTCs P0115, P0116, P0117 or P0118 are set simultaneously with DTC P0125, the Engine Coolant Temperature (ECT) sensor may have an open or a short circuit. Troubleshoot those DTCs first.
- Read freeze frame data using a Techstream. Freeze frame data record 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.
- CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0125)Â
- Connect a Techstream to the DLC3.
- Turn the ignition switch ON.
- Turn the tester ON.
- Select the following menu items: Powertrain / Engine and ECT / Trouble Codes.
- Read DTCs.
ResultÂ
RESULT REFERENCEDisplay (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 CHARTÂ (See DIAGNOSTIC TROUBLE CODE CHART )
A: Go to next stepÂ
- INSPECT WATER INLET WITH THERMOSTAT (THERMOSTAT)Â
- Remove the water inlet with thermostat (See REMOVAL ).
- Check the valve opening temperature of the thermostat.
Standard: 80° to 84°C (176° to 183°F)Â
HINT:
In addition to the above check, confirm that the valve is completely closed when the temperature is below the standard.
- Reinstall the water inlet with thermostat (See INSTALLATION ).
NG: REPLACE WATER INLET WITH THERMOSTATÂ (See REMOVAL )
OK: Go to Next StepÂ
- CHECK COOLING SYSTEMÂ
- 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 SYSTEMÂ
OK: REPLACE ENGINE COOLANT TEMPERATURE SENSORÂ (See REMOVAL )
NO RELATED
Use the Manual With the Right Hardware
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.