Code 3145 - ECT Sensor Malfunction

Inspect condition of connector. Clean and repair as needed. Faulty coolant temperature sensor can cause incorrect idle RPM during cold start-up condition and rich air/fuel mixture.
If no scan tester is available, go to next step. Connect and operate scan tester according to manufacturer's instructions. Read service data item No. 24. If scan tester display is approximately equal to actual engine temperature, go to next step. If scan tester display is not approximately equal to actual engine temperature, go to step 4).

Remove coolant temperature sensor. Immerse sensor in water. Measure sensor resistance while increasing water temperature. See COOLANT TEMPERATURE SENSOR RESISTANCE SPECIFICATIONS. If resistance is within specification, go to next step. Replace sensor if resistance measured is not within specification.

COOLANT TEMPERATURE SENSOR RESISTANCE SPECIFICATIONS

Coolant Temperature °F (°C)	Ohms
-22 (-30)	22,220-31,780
14 (-10)	8160-10,740
32 (0)	5180-6600
68 (20)	2270-2730
104 (40)	1059-1281
140 (60)	538-650
176 (80)	290-354
194 (90)	217-269

Turn ignition off. Unplug engine coolant temperature harness connector. Turn ignition on. Measure voltage between Yellow/Red wire of harness connector and vehicle ground. If voltage is 4.6-4.8 volts, go to next step. If voltage is not 4.6-4.8 volts, repair Yellow/Red wire between sensor and ECM connector terminal No. 45.
Test Black wire at sensor harness connector for continuity to ground. If continuity exists, go to next step. If continuity does not exist, repair Black or Black/Yellow wire to ECM harness connector terminal No. 30. See appropriate wiring diagram in WIRING DIAGRAMS section.
Temporarily substitute known good ECT sensor, then retest system. If sensor is okay, temporarily substitute known good ECM, then retest system.