2005 Nissan-Datsun Sentra Base, AutomaticFACTORY OEM SERVICE PROCEDURE

Component Description

NOTE: If DTC P0125 is displayed with P0117, P0118, first perform trouble diagnosis for "DTC P0117, P0118 ECT SENSORΒ ".

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
G02449822Courtesy of NISSAN MOTOR CO., U.S.A.

Reference dataΒ 

Fig 2: ECT Sensor Temperature Versus Resistance Graph
G02449823Courtesy of NISSAN MOTOR CO., U.S.A.
ECT SENSOR RESISTANCE/VOLTAGE SPECIFICATIONS

Engine coolant temperature Β°C (Β°F) Voltage(1)V Resistance kΞ©
20 (68) 3.5 2.1 - 2.9
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 terminal 73 (Engine coolant temperature sensor) and ground.
CAUTION: Do not use ECM ground terminals when measuring input/output voltage. Doing so may damage the ECM's transistor. Use ground other than ECM, such as body ground.
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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.