Servo Motor Potentiometer Defrost Circuit Failure
The defrost blend door servo motor's position sensor (potentiometer) is sending an invalid signal to the climate control module. Think of it like a dimmer switch that's broken—the system can't tell where the dial actually is.
The ECU monitors the potentiometer voltage output from the defrost servo motor to confirm the blend door position. The sensor should produce a linear voltage signal (typically 0.5V to 4.5V) that changes as the motor moves. If voltage is out of range, shorted, or absent, a fault is recorded.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Potentiometer Voltage | 0.5V to 4.5V linear sweep | Below 0.1V, above 4.9V, or erratic values |
| Motor Response Time | Voltage change within 2 seconds | No voltage change or timeout after command |
Code B1268 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, B1268 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.