Questiondear sir
a few days ago i asked for your advise where the location of temperature sensor is on the engine bay.am sorry to ask again becouse i did not get the first reply from you.
my hyundai lantra1994 1.8ltr auto returned a fault code 2 when tested.the tester told me it was the coolant temp sensor is faulty.am not sure where the coolant temperature sensor is on the engine.the problem is,if the car is cold the CHECK ENGINE light comes ON after driving for about 2mins and by any chance i stop at traffic lights the car will struggle to move.but after the engine gets hot it will move with no difficulty.sometimes i turn the engine OFF and then ON again and the CHECK ENGINE light will not come on again.is it a multiple of problems or its just the sensor? thank you in advance.
AnswerENGINE COOLANT TEMPERATURE SENSOR DIAGNOSIS
DESCRIPTION:
The engine coolant temperature sensor is located in the coolant passage of the cylinder head. It detects engine coolant temperature and sends signals to the powertrain control module (PCM). The engine coolant temperature sensor uses a thermistor which is sensitive to changes in temperature. The electric resistance of a thermistor decreases in response to a rise in temperature. Thus, when the temperature increases, the output voltage decreases. The PCM determines engine coolant temperature by the sensor output voltage and provides optimum fuel enrichment when the engine is cold.
This bulletin provides diagnosis and repair procedures for engine coolant temperature sensors.
DIAGNOSTIC PROCEDURES:
DTC: Diagnostic Trouble Code
PCM: Powertrain Control Module
ECT: Engine Coolant Temperature
DIAGNOSTIC HINTS:
If the fast idle speed is not high enough or if the engine produces dark smoke during engine warm-up operation, a malfunctioning engine coolant temperature sensor might be the cause.
If the thermostat opening state is abnormal and causes overcooling, the Diagnostic Code (DTC) for the engine coolant temperature sensor can be set.
The Malfunction Indicator Lamp (MIL) is on or the DTC is set under the following conditions:
When the engine coolant temperature is detected by the sensor as below -40°C or above 120°C.
If the engine coolant temperature does not increase at least 5°C, even though 130 seconds or more have elapsed after starring the engine.
USING A VOLTMETER:
CHECK ITEM COOLANT TEMPERATURE TEST SPECIFICATION
Engine coolant temperature sensor output voltage (ECT Sensor side connector pin No. 4 or ECM harness side connector pin No.19)
When 0°C
4.05V
When 20°C
3.44V
When 40°C
2.72V
When 80°C
1.25V
USING A SCAN TOOL:
CHECK ITEM DATA DISPLAY CHECK CONDITIONS COOLANT TEMPERATURE TEST SPEC.
Engine coolant temperature sensor
Sensor temperature
Ignition switch: ON or engine running
When -20°C (4°F)
-20°C
When 0°C (32°F)
0°C
When 20°C (680°F)
20°C
When 40°C (104°F)
40°C
When 80°C (176°F)
80°C
HARNESS INSPECTION PROCEDURES:
SENSOR INSPECTION:
Remove the ECT sensor from the intake manifold.
With the temperature sensing portion of the ECT sensor immersed in hot water, check resistance.
If the resistance deviates from the standard value (as shown on the chart), replace the sensor.
TEMPERATURE °C (°F) RESISTANCE (K OHMS)
-30 (-22)
22.22-31.78
-10 (14)
8.16-10.74
0 (32)
5.18-6.60
20 (68)
2.27-2.73
40 (104)
1.059-1.281
60 (140)
0.538-0.650
80 (176)
0.298-0.322
90 (194)
0.219-0.243
INSTALLATION:
Apply sealant (LOCTITE962T or equivalent) to the threaded portion of the sensor.
Install ECT sensor and torque to 11-15 lb. ft.
Reconnect the harness connector securely.
