Component Location
General Description
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.
DTC Description
Checking the engine coolant temperature under detecting condition, if the engine coolant temperature's signal is temporarily stuck above the lowest enable temperature to enable other diagnostic or the coolant temperature exceeds the threshold temperature under normal operation loads or the difference between its current temperature and startup temperature is less than threshold value over predeterminated period, ECM sets P0116.
DTC Detecting Condition
Item | Detecting Condition | Possible cause |
DTC Strategy | Monitor the engine coolant temperature
| ECTS
|
Enable Conditions | Case1 | Shutdown time > 180 minutes
Intake air-temperature at start-up < 40?(104?)
No disabling faults(ECTS)
Engine running > 60 seconds
Minimum airflow is satisfied for a certain time.
|
Case2 | Coolant sensor is normal
No disabling faults present(DTCs related to MAFS/MAPS, catalyst, fuel system or engine oil temperature sensor)
Coolant Temperature at startup < 45?( 113 °F)
Engine running state
Coolant temperature > 50?( 122 °F)
Intake air temperature < 35?( 95 °F)
|
Case3 | Engine running state
Before startup, leave it under IG-OFF over 6 hours
No disabling faults(DTCs related to HO2S, MAFS/MAPS, catalyst, fuel system, ECTS, or misfire)
|
Threshold value | Case1 | When the start-up engine coolant temperature does not rise by 1.5 ?(2.7?).
|
Case2 | Coolant temperature = 110? (230 °F) (Average airflow< 50 g/sec and filtered airflow< 40 g/sec)
|
Case3 | The difference between the current its temperature and the startup temperature < 1.5 ?(2.7?)
|
Diagnosis Time | Case1 | Immediately
|
Case2 | Once per driving cycle ( about 2 minutes)
|
Case3 | Once per driving cycle (More than 120 seconds failure)
|
MIL On Condition | NO MIL ON(DTC only)
|
Specification
Temp. (?) | Resistance (k?) | Temp. (?) | Resistance (k?) |
-40 | 48.14 | 40 | 1.15 |
-20 | 14.13 ~ 16.83 | 60 | 0.59 |
0 | 5.79 | 80 | 0.32 |
20 | 2.31 ~ 2.59 | | |
Diagnostic Circuit Diagram
Signal Waveform & Data
Fig.1) Normal waveform of ECTS at 77? (171.1?)
Fig.2) Normal data of IATS & ECTS & EOTS at ig on
Fig.3) Normal data of IATS & ECTS & EOTS after warming up.
The output signals of IATS & ECTS change smoothly without any rapid changes. These 2 sensor have almost the same characteristic signal during the early period after start. It means that the temperatures of intake air and engine coolant are depended on the temperature of atmosphere. Meanwhile, During engine warm up the output signal of the ECT will change quicker than the IAT signal. even it may not change almost.