What does it mean?
B1271 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Sliding Door Optical Sensor-1 Output Stuck Low .
Symptoms
- The power sliding door will not close, or closes and then immediately reverses
- The door has to be operated manually
- A chime sounds or a warning appears when the door is commanded
- Door operation is slower than normal or hesitates part way through travel
- The fault may only appear in wet or freezing weather
Likely causes
- Optical sensor lens or emitter contaminated by dirt, ice, or road film so the beam never breaks
- Sensor signal wire shorted to ground inside the sliding door harness
- Internal failure of the optical sensor unit
- Broken conductor in the flexible harness that runs into the sliding door, a common failure from repeated opening
- Water intrusion into the sensor connector inside the door
- Failed input circuit in the sliding door control module
How to fix it
- Clean the optical sensor lens and the opposing receiver or reflector, then retest the door
- Watch the sensor status in live data while blocking and unblocking the beam by hand
- Inspect the flexible harness section between the body and the sliding door for broken conductors and chafing
- Unplug the sensor and check the signal wire for a short to ground with the module connector released
- Confirm the sensor supply voltage and ground are correct at the connector
- Repair the harness or replace the optical sensor, then cycle the door several times to verify normal operation