An Engine Coolant Temperature Sensor (ECTS) monitors the temperature of the coolant. This input is used by the PCM for engine control and as an enabling criteria for related diagnostics. The air flow coming into the engine is accumulated and used to determine if the engine has been driven within conditions that would allow the engine coolant to heat up normally to the thermostat regulating temperature. If the coolant temperature does not reach regulating temperature of the thermostat, diagnostics that use engine coolant temperature as enabling criteria, may not run when expected.This DTC will set when there has been excessive time to reach a minimum coolant temperature required for closed loop fuel control.
The purpose of this diagnosis is to monitor the minimum coolant temperature that enables lambda closed loop control after start. Minimum coolant temperature to run lambda control must be reached before the threshold time predetermined according to intake air temperature at start. If the lambda control is not active because of low engine coolant temperature within predetermined minimum time after start, the PCM sets DTC P0125.
Item | Detecting Condition | Possible Cause |
DTC Strategy | ● Check time to closed loop control start with coolant temperature model. | ● Contact resistance in connectors. ● Faulty cooling system. ● Faulty thermostat. ● Faulty ECT sensor. |
Enable Conditions | ● Minimum time after engine start versus intake air temperature at start : 1) 2minutes for intake air temp. ＞ 10℃(50°F) 2) 5minutes for -7℃(19°F) ＜ Intake air temp. ＜ 10℃(50°F) ● 6 ＜ Battery voltage(V) ＜16 | |
Threshold value | ● Measured coolant temperature ＜ 5°C(41°F) When modeled coolant temperature ＞ 5℃(41°F) | |
Diagonostic Time | ● Immediate. | |
Fall Safe | ● Calculated engine coolant temperature is used for engine control. ● Cooling/Condenser fan is active with MAX speed. ● EVAP. emission control function is controlled in minimum operation mode. |
[ECTS]
Temp.(°C) | Temp.(°F) | Resistance(kΩ) |
-20 | -4 | 14.13 ~ 16.83 |
0 | 32 | 5.79 |
20 | 68 | 2.31 ~ 2.59 |
40 | 104 | 1.15 |
60 | 140 | 0.59 |
80 | 176 | 0.32 |
[THERMOSTAT]
Thermostat | Normal Parameter |
Valve Opening Temp. | 80~84°C(176~183°F) |
Valve Closing Temp. | 77°C(170.6°F) |
Full Open Lift | Above 8mm at 95°C(203°F) |
