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 5V 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.
PCM sets DTC P0116 if the PCM detects stuck low, high or implausible high ECT signal.
Item | Detecting Condition & Fail Safe | Possible Cause | |
DTC Strategy | Case1 |
•
Signal Stuck Low | 1. Poor connection or damaged harness 2. Faulty ECT sensor 3. Faulty cooling system |
Case2 |
•
Signal Stuck High | ||
Case3 |
•
Signal implausible high | ||
Enable Conditions | Case1 |
•
No relevant failure
•
6V< Battery voltage
•
Coolant temperature at Start < 76℃(169℉) | |
Case2 |
•
No relevant failure
•
11V< Battery voltage <16V
•
Coolant temperature at Start >76℃(169℉)
•
-10℃(14℉)< Intake air temp. <70℃(158℉)
•
-10℃(14℉)< Ambient temperature
•
More than 250 sec. (cumulative) Part Load driving condition(engine rpm >1400,vehicle speed >22 mph and MAF >20 kg/h)
•
More than 200 sec. (cumulative) Low Load driving condition(trailing fuel cut off or idle with vehicle speed <12mph) | ||
Case3 |
•
No relevant failure
•
Oil temp. at engine stop of previous driving cycle >70℃(158℉)
•
Coolant temp. at engine stop of previous driving cycle >70℃(158℉)
•
Oil temp. at start <35℃(95℉)
•
ntake air temp. at start <35℃(95℉) | ||
Threshold Value | Case1 |
•
Modeled coolant temp. increase > Threshold But measured coolant temp. increase <Threshold | |
Case2 |
•
Coolant temperature signal variation since engine Start < 2.25 ℃(4℉) | ||
Case3 |
•
Coolant temperature in start > 53 ℃(127℉)(In case of coolant temp.> threshold but oil temp. & intake air temp < threshold) | ||
Diagnostic Time |
•
Immediate | ||
MIL On Condition |
•
2 Driving Cycles | ||
Temp.(℃) | Temp.(℉) | Resistance(㏀) | Temp.(℃) | Temp.(℉) | Resistance(㏀) |
-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 |
