Code Definition

B12D3 (23) — Driver’s Door Lock Status Signal Stuck Low

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

About B12D3

B12D3 is a manufacturer-specific body diagnostic trouble code recorded for Mazda vehicles. It belongs to the B-prefix family of codes, which covers body, interior, airbag, or comfort-electronics faults.

When B12D3 is stored, the module has detected a signal or supply voltage lower than the expected operating range.

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.

B12D3 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 Body Control Module (BCM) monitors the driver's door lock status circuit to determine in real time whether the door is in the locked or unlocked state, using a switch contact within the door lock actuator assembly that pulls the BCM sense input low at one extreme of travel. DTC B12D3:23 is set when the BCM detects that the lock status signal remains in a low (grounded) state continuously, regardless of the lock command issued or the actual mechanical position of the lock cylinder. The :23 sub code conforms to ISO 15031 part 6 and specifically denotes a signal that is permanently stuck low,...

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