Mirror Passenger Horizontal Feedback Potentiometer Circuit Failure
The passenger side mirror's position sensor (potentiometer) isn't sending the right electrical signal to the car's computer, like a volume knob that's broken and won't tell your stereo what level it's at. The ECU can't confirm the mirror is moving to the correct position.
The ECU monitors the voltage output from the passenger mirror's horizontal position potentiometer during mirror adjustment. It compares the actual voltage feedback against expected values based on the control signal sent. If voltage falls outside normal operating range or shows erratic behavior, the ECU triggers a fault.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Potentiometer Voltage | 0.5–4.5V (proportional to mirror position) | <0.2V or >4.8V, or no signal detected |
| Signal Continuity | Smooth voltage transition during mirror movement | Dropouts, noise, or stuck values |
Code B2312 is a low-severity fault. Your vehicle is generally safe to drive to a workshop for diagnosis. However, do not ignore it indefinitely — low-severity codes often indicate developing problems that become expensive if neglected. Book a diagnostic appointment within 2–4 weeks. If you notice any additional symptoms (rough running, power loss, unusual smells), treat it as higher priority.
Once the fault is repaired, B2312 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.