Hyundai Sonata LF: Engine Control System / Engine Coolant Temperature Sensor (ECTS) Description and Operation
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 that changes resistance
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.

Inspection
1.
Connect a GDS on the Data Link Connector (DLC).
2.
Measure the output voltage of the BPS at idle and IG ON.
Specification: Refer to "Specification"
Removal
1...
Other information:
OBD-II review
1. Overview
The California Air Resources Board (CARB) began regulation of
On Board Diagnostics (OBD) for vehicles sold in California beginning
with the 1988 model year. The first phase, OBD-I, required monitoring of
the fuel metering system, Exhaust Gas Recirculation (EGR) system and
additional emission related components...
Description
The SMART KEY system is a system that allows the user to
access and operate a vehicle in a very convenient way. To access the
vehicle, no traditional key or remote control unit is needed.
The user carries a SMART KEY FOB which does not require any
conscious actions by the user (e...