2. Check ECT Sensor Power Supply Circuit

WARNING: This page is about a different car, the 2004 Infiniti Q45. However, it is still accessible from the selected car via links, so may be relevant.

Disconnect engine coolant temperature (ECT) sensor harness connector.

Fig 1: Locating engine coolant temperature sensor
Courtesy of NISSAN MOTOR CO., U.S.A.
Turn ignition switch ON.
Check voltage between ECT sensor terminal 1 and ground with CONSULT-II or tester.
1. Voltage: Approximately 5V

OK or NG

OK: GO TO 4. CHECK ECT SENSOR GROUND CIRCUIT FOR OPEN AND SHORT .

NG: GO TO 3.

Fig 2: Checking voltage between ECT sensor terminal 1 & ground

G00760446

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