What does it mean?
B1211 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Front Center Left Sensor Fault .
Symptoms
- Parking aid warning message or lamp illuminated
- System beeps continuously as soon as it arms, or refuses to arm at all
- Dead zone in the middle of the front bumper while the outer sensors still detect
- False obstacle warnings while driving forward slowly
- Front distance display shows no segment for that sensor
- Automatic parking function disabled
Likely causes
- Failed sensor element or water inside the sensor housing
- Dirt, ice, snow or a thick layer of paint on the sensor face after bumper refinishing
- Sensor loose in its holder or displaced by a parking knock, so it aims at the ground
- Damaged bumper harness where it passes behind the grille or crash bar
- Corroded terminals in the sensor connector after exposure to spray and salt
- Poor supply or ground to the parking aid module, or a blown fuse
- Parking aid module input fault or a communication fault with the sensor bus
How to fix it
- Clean the sensor face and look closely for paint build-up, cracks or a sensor sitting proud of the bumper
- Watch the individual sensor readings in live data while an object is moved towards the front centre area
- Listen for the ticking of each sensor with the system armed to identify the silent one
- Inspect the harness behind the bumper for chafe against the crash bar and for pinched sections
- Check the connector for corrosion and green deposits, and confirm supply and ground at the module
- Swap the suspect sensor with a good one from another position to see whether the fault moves with it
- Fit the correct replacement sensor or repair the harness, then clear the code and verify all sensors report