What does it mean?
B1849 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Sunroof Motor Control Circuit/Performance (Stalled) .
Symptoms
- Roof moves partway then stops or reverses
- Grinding, clicking or straining noise from the roof while it moves
- Panel ends up out of alignment, causing wind noise or a water leak
- One-touch operation lost, the switch must be held
- Sunroof stops responding completely for a while after a few attempts, then works again when it cools
Likely causes
- Dry, dirty or gummed sunroof guide rails creating high friction
- Broken or displaced guide shoe or drive cable so the panel binds
- Ice, leaves or grit in the tracks jamming the panel
- Sunroof motor worn, with high current draw or failing brushes
- Voltage drop at the motor connector from corrosion or a poor ground
- Sunroof position never initialised after a battery disconnect or a repair
- Module output driver weak so the motor never reaches full speed
How to fix it
- Operate the roof and note exactly where it binds or slows down
- Clean the tracks and guides thoroughly and apply the correct grease, not a general purpose spray
- Inspect the drive cables and guide shoes for cracks, wear or displacement
- Measure motor current draw during travel and compare with the effort needed by hand
- Check the voltage at the motor connector under load and test the ground
- Reinitialise or normalise the sunroof after any battery disconnect or mechanical repair
- Replace the motor if the current is still high with the panel disconnected from the drive