General Information

Component Location





General Description

A water temp sensor located at heater unit detects coolant temperature. It contains negative type thermistor whose resistance value is in inverse proportion to temperature. Resistance of water sensor that varies with temperature makes signal voltage of A/C ECU change. In this way A/C ECU detects temperature. Signal of water sensor is used for cold engine lockout control - When the driver operates the heater before the engine is warmed up enough, to prevent driver from unpleasantness of cold air. the heater control unit reduces blower motor speed until coolant temperature reaches the threshold value.

DTC Description

The ECM sets DTC B1203 if there is a short circuit in water temp sensor signal harness or the measured voltage value of the sensor is less than the threshold value (0.1V)

DTC Detecting Condition





Schematic Diagram





Signal Waveform

** Resistance value of water temp sensor as a function of temperature.