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.
Circuit Description
An Engine Coolant Temperature (ECT) sensor monitors the temperature of the coolant. This input is used by the Engine Control Module (ECM) for engine control and as an enabling criteria for some diagnostics.
The air flow into the engine is accumulated and used to determine if the vehicle has been driven within the conditions that would allow the engine coolant to heat up normally. If the coolant temperature does not increase normally, the diagnostics that use engine coolant temperature as enabling criteria may not run when expected. This DTC will run continuously.
If ECM detects the calibrated amount of air flow and engine run time have been met, and the engine coolant has not met the calibrated temperature, DTC P0125 sets.
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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.