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 PCM is supplied to the ECTS via a resistor in the PCM. That is, the resistor in the PCM 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 PCM increases the fuel injection duration and controls the ignition timing using the information of engine coolant temperature to avoid engine stalling and improve drivability.
Checking the engine coolant temperature under detecting condition, if if the difference between its current temperature and startup temperature is less than threshold value over predeterminated period, PCM sets P0115.
Item | Detecting Condition | Possible cause | |||||
DTC Strategy | ● Monitor the engine coolant temperature | ● ECTS | |||||
Enable Conditions | ● 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 | ● The difference between the current its temperature and the startup temperature ＜ 3 ℃(5.4℉) | ||||||
Diagnosis Time | ● Once per driving cycle (More than 120 seconds failure) | ||||||
MIL On Condition | ● No MIL ON (DTC only) | ||||||
Temp. (℃/℉) | Resistance (kΩ) | Temp. (℃/℉) | Resistance (kΩ) | ||||
-40(-40) | 48.14 | 40(104) | 1.15 | ||||
-20(-4) | 14.13 ~ 16.83 | 60(140) | 0.59 | ||||
0(32) | 5.79 | 80(176) | 0.32 | ||||
20(68) | 2.31 ~ 2.59 |
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The output signals of IATS ＆ ECTS change smoothly without any rapid changes. Those have almost 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 the warming up, the output signal of ECTS is going up increasingly. but, the output signal of IATS changes a little bit. even it may not change almost. It means that the heat of engine does not affect on the temperature of intake air.
Check DTC Status
Connect scantool to Data Link Connector(DLC).
IG "ON".
Select "DTC" button, and then Press "DTC Status" to check DTC's information from the DTCs menu.
Read "DTC Status" parameter.
Is parameter displayed "Present fault"?
▶ Go to "Component Inspection" procedure.
▶ Fault is intermittent, go to "Verification of vehicle Repair" procedure.
IG "OFF" and disconnect ECTS connector.
Remove it.
Measure resistance between signal and ground terminals of ECTS connector as the temperature rises.
Temp. (℃/℉) | Resistance (kΩ) | Temp. (℃/℉) | Resistance (kΩ) | ||||
-40(-40) | 48.14 | 40(104) | 1.15 | ||||
-20(-4) | 14.13 ~ 16.83 | 60(140) | 0.59 | ||||
0(32) | 5.79 | 80(176) | 0.32 | ||||
20(68) | 2.31 ~ 2.59 |
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Are the measured resistance within specification?
▶ Clear DTC and Test-drive under enable conditions above-mentioned. After the test, If this DTC is set, recheck it thoroughly. If not, it is intermittent fault, go to "Verification of vehicle Repair" procedure.
▶ Substitute with a known - good ECTS and check for proper operation.
▶ If the problem is corrected, Go to "Verification of Vehicle Repair"procedure.
After a repair, it is essential to verify that the fault has been corrected.
Connect scantool and select "DTC" button.
Press "DTC Status" button and confirm that "DTC Readiness Flag" indicates "Completed". If not, drive the vehicle within conditions noted in the freeze frame data or enable conditions
Read "DTC Status" parameter
Is parameter displayed "History(Not Present) fault"?
▶ System performing to specification at this time. Clear the DTC.
▶ Go to the applicable troubleshooting procedure.
