Operation CHARM: Car repair manuals for everyone.

General Information





Component Location





General Description

Humidity sensor located at heater control unit detects in-car humidity for in-car humidity control. If ambient air temperature or in-car humidity is outside a specified range, A/C will be activated to control in-car humidity to prevent fogging of the windows.

DTC Description

The ECM sets DTC B1200 if there is an open circuit in humidity sensor signal harness or the measured frequency value of sensor is more than the threshold value (about 7,100 Hz)

DTC Detecting Condition





Schematic Diagram





Signal Waveform

** Frequency value of humidity sensor as a function of humidity.