Kia Optima: Engine Control System / Engine Coolant Temperature Sensor (ECTS)

Kia Optima DL3 2019-2023 Service and Repair Manual / Engine Control / Fuel System / Engine Control System / Engine Coolant Temperature Sensor (ECTS)

Specifications

Specification

Temperature		Resistance (kΩ)
°C	°F	Resistance (kΩ)
45	113	244.8 - 281.4
55	131	162.5 - 186.5
60	140	133.5 - 153.5
71	159.8	88.93 - 102.13
85	185	55.16 - 63.36
110	230	26.02 - 29.82
125	257	17.5 - 19.7

Description and operation

Description

•	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 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.

Components and components location

Components Location

1. Engine Coolant Temperature Sensor (ECTS)

Schematic diagrams

Circuit Diagram

Harness Connector

Repair procedures

Inspection

The engine control system can be more quickly diagnosed for troubles by using the vehicle diagnostic system (KDS). (Refer to "DTC guide")

KDS provides the following information.

(1)	Self diagnosis : Inspects and displays diagnostic trouble code (DTC)

(2)	Sensor data : Checks the system input/output value status

(3)	Forced operation : Checks the system operating status

(4)	Additional function : Controls system options, zero point adjustment and other functions

Components Inspection

1.	Turn ignition switch OFF.

2.	Disconnect the engine coolant temperature sensor connector.

3.	Remove the sensor.

4.	After immersing the thermistor of the sensor into engine coolant, measure resistance between ECTS signal terminal and ground terminal.

Check that the resistance is within the specification.

Temperature		Resistance (kΩ)
°C	°F	Resistance (kΩ)
45	113	244.8 - 281.4
55	131	162.5 - 186.5
60	140	133.5 - 153.5
71	159.8	88.93 - 102.13
85	185	55.16 - 63.36
110	230	26.02 - 29.82
125	257	17.5 - 19.7

Removal

1.	Disconnect the negative battery terminal.

2.	Remove the battery. (Refer to Engine Electrical System - "Battery")

3.	Disconnect the engine coolant temperature sensor connector (A).

Remove the ECTS (A).

Tightening torque :

29.4 - 39.2 N·m (3.0 - 4.0 kgf·m, 21.7 - 28.9 lb·ft)

Note that engine coolant may be flow out from the engine coolant temperature control assembly when removing the sensor.

Installation

•	Install the component with the specified torque.

•	Note that internal damage may occur when the component is dropped. If the component has been dropped, inspect before installing.

•	Apply the engine coolant to the O-ring.

1.	Install in the reverse order of removal.

2.	Refill the engine cooling system with engine coolant. (Refer to Engine Mechanical System - "Coolant")

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