Diagnostic Procedure

Turn ignition off. Disconnect ECT sensor harness connector. See Fig 1 or Fig 2 . Turn ignition on. Measure voltage between ground and ECT sensor harness connector terminal No. 1 (Light Green/Red wire). If voltage is about 5 volts, go to next step. If voltage is not about 5 volts, go to next step.
Repair open or short on Light Green/Red wire between ECM and ECT sensor.
Turn ignition off. Check continuity between engine ground and ECT sensor harness connector terminal No. 2 (Black/White wire on 2.4L models; Brown wire on 3.3L models). Continuity should exist. Also, check circuit for short to voltage. If problem is found, go to next step. If problem is not found, go to step 5 .
Repair open or short on sensor ground circuit between ECM and ECT sensor.
Remove ECT sensor, and place in heated water. Measure resistance between sensor terminals, with water at specified temperatures. See ENGINE COOLANT TEMPERATURE SENSOR RESISTANCE table. If resistance is as specified, go to next step. If resistance is not as specified, replace ECT sensor.
No problem is indicated at this time. Problem may be intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article.

ENGINE COOLANT TEMPERATURE SENSOR RESISTANCE

Temperature - °F (°C)

⁽¹⁾ Ohms

14 (-10)

7000-11,400

68 (20)

2100-2900

122 (50)

680-1000

194 (90)

236-260

⁽¹⁾	Resistance should decrease as temperature increases. See Figure .

Fig 1: Locating ECT Sensor (2.4L)

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

Fig 2: Locating ECT Sensor (3.3L)

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