Code Definition

B1031 — Air Thermo Sensor System Circuit Shorted

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

About B1031

B1031 is a manufacturer-specific body diagnostic trouble code recorded for Mitsubishi vehicles. It belongs to the B-prefix family of codes, which covers body, interior, airbag, or comfort-electronics faults.

When B1031 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.

B1031 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 Air Thermo Sensor on Mitsubishi vehicles is a negative temperature coefficient (NTC) thermistor used by the climate control system to measure cabin, ambient, or discharge air temperature depending on its location within the HVAC ducting. The sensor resistance decreases as temperature rises, and the climate control module reads the resulting voltage on its reference supply circuit to calculate a temperature value for controlling blend door position, compressor operation, and blower speed. DTC B1031 is set when the climate control module detects that the sensor signal voltage has dropped bel...

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