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 P0116 if the ECM detects stuck low, high or implausible high ECT signal
Item | Detecting Condition & Fail Safe | Possible Cause | |
DTC Strategy | case 1) | ● Signal stuck Low | ● Contact resistance in connections. ● Insufficient Engine Coolant ● Faulty Thermostat ● Faulty ECT sensor |
case 2) | ● Signal stuck High | ||
Enable Conditions | case 1) | ● No relevant failure ● 6 < Battery voltage | |
case 2) | ● No relevant failure ● Engine oil temp. at engine stop of previous DC > 70℃(158℉) ● Coolant temp. at engine stop of previous driving cycle > 70℃(158℉) ● Engine oil temperature at Start < 35℃(95℉) ● Intake Air Temperature at Start < 35℃(95℉) | ||
Threshold Value | case 1) | ● Coolant temperature signal variation since engine Start < 2°C(4°F) when coolant temp. below 40°C(104°F) at start | |
case 2) | ● Engine coolant temperature at start > 53°C(127°F) | ||
Diagnostic Time | case 1) | ● 10~30 minutes depends on coolant temp. at start | |
case 2) | ● Immediate | ||
Mil On Condition | ● 2 Driving Cycles | ||
Temp. (°C) | Temp. (°F) | Resistance (kΩ) | Temp. (°C) | Temp. (°F) | Resistance (kΩ) |
-20 | -4 | 14.1 ~ 16.8 | 40 | 104 | Approx. 1.2 |
0 | 32 | Approx. 5.8 | 60 | 140 | Approx. 0.6 |
20 | 68 | 2.3 ~ 2.6 | 80 | 176 | Approx. 0.3 |
