Code Definition

B1251 — Air Temperature Internal Sensor Circuit Open

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

About B1251

B1251 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 B1251 is stored, the module has detected an open (broken or disconnected) electrical path 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.

B1251 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 internal air temperature sensor, also called the cabin temperature sensor, is an NTC thermistor that reports cabin air temperature back to the climate control module for use by the automatic climate control system. The sensor is typically housed in the overhead console, dash near the windshield, or behind a vented grille, and many installations include a small aspirator fan that continuously draws cabin air across the element for a representative reading. DTC B1251 sets when the module detects that the sensor signal voltage has pulled up to its reference ceiling, consistent with an open ci...

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