Window Feedback Loss of Signal
The car's window control module lost electrical signal from a window position sensor, like a radio losing its station signal. The ECU can't tell where the window is or if it's moving correctly.
The ECU monitors voltage feedback from the window position sensor (potentiometer or switch) as the window moves up and down. It expects a continuous signal within a specific voltage range during operation. Loss of signal means the sensor is disconnected, shorted, or the wiring is broken.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Window Sensor Voltage | 0.5V to 4.5V (varying with position) | No signal or voltage out of range |
| Signal Continuity | Continuous feedback during window movement | Intermittent or absent signal |
Code B1236 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, B1236 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.