What does it mean?
B1859 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Driver Window Position Sensor Power Supply High .
Symptoms
- Auto up and auto down are disabled, only manual operation remains
- Anti-pinch protection no longer works
- Position data on the scan tool is implausible or reads maximum
- Window does not stop correctly at the top of its travel
- Code returns as soon as the window is operated
Likely causes
- Sensor supply wire shorted to battery voltage
- Wires crossed after a door harness, motor or regulator repair
- Corrosion bridging pins inside the motor or module connector
- Module voltage regulator failed high and pushing too much voltage onto the supply
- Aftermarket accessory tapped into the door harness feeding voltage backwards
- Damaged insulation in the hinge boot letting the supply touch a powered wire
How to fix it
- Measure the supply voltage with the sensor connector unplugged and the ignition on
- Unplug the module as well, if battery voltage is still present the short is external
- Compare the reading with the passenger side circuit as a healthy reference
- Inspect the connectors for corrosion or debris bridging adjacent pins
- Look for aftermarket taps, added lighting or alarm wiring in the door harness
- Repair the damaged section of harness or renew the connector
- Replace the motor and sensor unit or the module if the supply is still high, then relearn the window