DTC P0125: ECT Sensor: Description

WARNING: This page is about a different car, the 2011 Infiniti FX35. However, it is still accessible from the selected car via links, so may be relevant.

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.

Fig 1: Identifying ECT Sensor, Gasket And Terminal

Courtesy of NISSAN MOTOR CO., U.S.A.

TEMPERATURE RESISTANCE REFERENCE CHART

Engine coolant temperature [°C (°F)]

Voltage⁽¹⁾ (V)

Resistance (kΩ)

-10 (14)

4.4

7.0 - 11.4

20 (68)

3.5

2.10 - 2.90

50 (122)

2.2

0.68 - 1.00

90 (194)

0.9

0.236 - 0.260

⁽¹⁾	These data are reference values and are measured between ECM terminals 71 (Engine coolant temperature sensor) and 84 (Sensor ground).

Fig 2: Engine Coolant Temperature Resistance Graph

Courtesy of NISSAN MOTOR CO., U.S.A.