Water Temperature Sensor (WTS):

WATER TEMPERATURE (WTS) SENSOR
The Water temperature sensor installed in the water passage of the cylinder head detects the water temperature and emits signals to the ECU. This part employs a thermistor which is sensitive to changes in temperature. The electric resistance of the thermistor decreases in response to a temperature rise (NTC). The ECU determines water temperature by the sensor output voltage and provides optimum fuel enrichment when the engine is cold.

Circuit Diagram:

Sensor Checking

Using Hi-Scan (Pro):

Using Hi-scan (Pro)

Using Multi-meter
1. Remove the water temperature sensor from the intake manifold.

2. With the temperature sensing portion of the water temperature sensor immersed in hot water, check the resistance.

3. If the resistance deviates from the standard value greatly, replace the sensor.

Harness Inspection Procedures:

Troubleshooting Procedures:

Using Voltmeter:

Using Voltmeter

Troubleshooting Hints
If the fast idle speed is not adequate or the engine gives off dark smoke during warm-up, the engine coolant temperature sensor might be the cause.

Installation
1. Apply sealant LOCTITE 962T or the equivalent to the threaded portion.
2. Install the water temperature sensor and tighten it to the specified torque.

Tightening torque:
Engine coolant temperature sensor: 20 - 40 N.m (200 - 400 kg.cm, 14 - 29 lb-ft)

3. Securely connect the harness connector.

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

Coolant Temperature Sensor/Switch (For Computer): Testing and Inspection