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.
P0125 ECT Sensor: Description
The engine coolant temperature sensor is used to detect the engine coolant temperature. The sensor modifies a voltage signal from the ECM. The modified signal returns to the ECM as the engine coolant temperature input. The sensor uses a thermistor which is sensitive to the change in temperature. The electrical resistance of the thermistor decreases as temperature increases.
< Reference data >Β
| Engine coolant temperature [Β°C (Β°F)] | Voltage(1) (V) | Resistance (kΞ©) | ||
|---|---|---|---|---|
| -10 (14) | 4.4 | 7.0 - 11.4 | ||
| 20 (68) | 3.5 | 2.37 - 2.63 | ||
| 50 (122) | 2.2 | 0.68 - 1.00 | ||
| 90 (194) | 0.9 | 0.236 - 0.260 | ||
|
||||
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- β’ You smell fuel, burning insulation, or see smoke.
- β’ Brakes feel soft, pull hard to one side, or make grinding noises.
- β’ The engine overheats, stalls repeatedly, or misfires under load.
- β’ You are missing required tools, torque specs, or safe lifting equipment.
- β’ You are not confident in the next step or safety outcome.