What does it mean?
B1246 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Air Mix Potentiometer Short (High)-Driver .
Symptoms
- Driver side temperature stays at one extreme and cannot be adjusted
- Blend position feedback in live data is pegged at maximum and never moves
- The actuator may keep hunting or clicking as the module tries to correct an impossible position
- The passenger side temperature still works on dual zone systems
- Uneven cabin temperature and poor defrost performance
Likely causes
- Shorted or worn wiper track inside the driver air mix actuator potentiometer
- Feedback signal wire shorted to the reference voltage inside the harness
- Missing or high resistance sensor ground, which pushes the feedback voltage to the top of the range
- Water or corrosion inside the actuator connector bridging the reference and signal pins
- Harness pinched under the dash after previous repair work
- Reference or input circuit fault inside the climate control module
How to fix it
- Read the driver blend feedback voltage in live data while sweeping the temperature setting
- Unplug the actuator and measure the reference voltage and the ground quality at the connector
- Check the feedback wire for a short to the reference circuit with both ends disconnected
- Measure the actuator's internal potentiometer through its full travel; a pegged or jumpy reading condemns it
- Repair the shorted wiring or the poor ground first, since a bad ground produces exactly the same symptom
- Replace the air mix actuator if its feedback potentiometer is faulty, then run the calibration routine