Code B2321 indicates that the mirror control module has detected an open circuit in the horizontal feedback potentiometer. This sensor monitors the actual position of the mirror glass to ensure it moves accurately to the commanded location.
The internal resistive element of the horizontal position sensor has failed or worn through, creating an open circuit.
Wires leading to the mirror assembly are frayed, broken, or pinched, commonly occurring within the door hinge boot.
Water intrusion into the mirror housing has caused corrosion on the pins, interrupting the electrical signal.
The wiring harness connector is not fully seated or has vibrated loose from the mirror assembly.
An internal circuit failure within the mirror control module is unable to process the feedback signal.
Depending on the system design, the mirror may still move, but the vehicle will not be able to track its position for memory or automatic settings.
No. Because this is a 'circuit open' code, the failure is most likely located in the wiring or the sensor within the mirror assembly itself.
No. This is a body electronics code and is unrelated to the engine management system; replacing the PCM will not resolve this issue.