The engine coolant temperature sensor located in the engine coolant passage of the cylinder head. It detects the engine coolant teperature and relays signals to the ECU. It employs a thermistor, which is sensitive to changes in temperature. The electric resistance of a thermistor decreases in response to temperature rise. The ECU judges engine coolant temperture by the sensor output voltage and provides optimum fuel enrichment when the engine is cold.
When idling speed is not appropriate or blacksmoke arises it is likely to be a defect of engine coolant temperature sensor.
Check item | Data display | Check conditions | Coolant temp. | Set value (HI-SCAN) |
Engine coolant temperature sensor | Sensor temperature | ● Ignition switch : ON or engine running | -20℃ | -20℃ |
0℃ | 0℃ | |||
20℃ | 20℃ | |||
40℃ | 40℃ | |||
80℃ | 80℃ |
Remove the engine coolant temperature sensor from the engine coolant passage of the cylinder head.
With the temperature sensing portion of the engine coolant temperature sensor immersed in hot water, check resistance.
ECT sensor
Temperature (℃) | Resistance (㏀) |
-20 | 14.13 ~ 16.83 |
0 | 5.790 |
20 | 2.31 ~ 2.59 |
40 | 1.148 |
60 | 0.586 |
80 | 0.322 |
Gauge unit
Temperature (℃) | Resistance (Ω) |
60 | 125 |
85 | 42.6 ~ 54.2 |
110 | 22.1 ~ 26.2 |
125 | 15.2 |
If the resistance deviates from the standard value greatly, replace the sensor.
Apply sealant THREEBOND TB 2403 or equivalent to threaded portion.
Install engine coolant temperature sensor and tighten it to specified torque.
: 2.0 ~ 4.0 kg.m
Connect the harness connector securely.
