Operation CHARM: Car repair manuals for everyone.

General Information





Component Location





General Description

The in-car temperature sensor is located at heater control unit. It contains a thermistor which measures the temperature of the inside. The signal, decided by the resistance value which changes in accordance with perceived inside temperature, is delivered to heater control unit and according to this signal, the control unit regulates in-car temperature to intended value

DTC Description

The ECM sets DTC B1234 if there is an open circuit in in-car temp sensor signal harness or the measured resistance value of the sensor is more than the threshold value (about 509.57 Kohms)

DTC Detecting Condition





Schematic Diagram





Signal Waveform

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