Code Definition

B1856 — Climate Control Air Temperature Internal Sensor Motor Circuit Short To Ground

System: Body  |  Type: Manufacturer-Specific  |  Make: Generic

About B1856

B1856 is a manufacturer-specific body diagnostic trouble code. It belongs to the B-prefix family of codes, which covers body, interior, airbag, or comfort-electronics faults.

When B1856 is stored, the module has detected a short-circuit (voltage pulled to ground or to supply) in the monitored circuit; and a sensor-related fault — the reported value from the named sensor is out of spec.

Scanning & clearing: Body (B) codes are often stored in the body control module, airbag module, or climate module. A basic OBD-II tool usually will not read body codes — an enhanced or OEM-level scan tool is typically required.

B1856 is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

The climate control module relies on an interior cabin air temperature sensor for automatic blend door and fan control, and the sensor assembly includes a small aspirator motor that the module drives to circulate cabin air across the thermistor for accurate temperature sampling. DTC B1856 is set when the climate control module detects the aspirator motor drive circuit shorted to chassis ground, causing the motor driver pin to be held at near zero volts and producing an overcurrent condition when the module attempts to switch the motor on. When this code is set, the aspirator motor typically do...

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