The Engine Coolant Temperature Sensor (ECTS) is located in the engine coolant passage of the cylinder head for detecting the engine coolant temperature. The ECTS uses a thermistor whose resistance changes with the temperature. The electrical resistance of the ECTS decreases as the temperature increases, and increases as the temperature decreases. The reference 5 V in the ECM is supplied to the ECTS via a resistor in the ECM. That is, the resistor in the ECM and the thermistor in the ECTS are connected in series. When the resistance value of the thermistor in the ECTS changes according to the engine coolant temperature, the output voltage also changes.
During cold engine operation the ECM increases the fuel injection duration and controls the ignition timing using the information of engine coolant temperature to avoid engine stalling and improve drivability.
ECM sets DTC P0118 if the ECM detects signal voltage higher than the possible range of a properly operating ECTS.
Item | Detecting Condition | Possible Cause |
DTC Strategy | ● Voltage range check | ● Short to battery in signal harness ● Open in signal or ground circuit ● Contact resistance in connections. ● Defective ECT sensor |
Enable Conditions | ● 6 ≤ Battery voltage ≤ 16V ● 60 seconds after "START" in case of short circuit to B+ or open circuit when ITAS is below -30 ℃ (86 ℉). | |
Threshold Value | ● Measured coolant temperature < -38℃(-36.4℉) | |
Diagnostic Time | ● 5 sec. | |
Fail Safe | ● The limp-home value of ECTS depends on intake air temperature. |
Temperature | Resistance | Temperature | Resistance | ||
(℃) | (℉) | (㏀) | (℃) | (℉) | (㏀) |
-20 | -4 | 14.13 ~ 16.83 | 40 | 104 | 1.15 |
0 | 32 | 5.79 | 60 | 140 | 0.59 |
20 | 68 | 2.31 ~ 2.59 | 80 | 176 | 0.32 |
