BMW F30/F31 lighting faults
F31: headlight adjustment motor fault and the light stays on, what is the cause?
The fault codes may be 8041B6 and D90D2F. Replacing the control board does not necessarily help. The cause may be in the wiring harness, where a wire has broken because of chafing and corrosion. Have the BMW dealer repair it.
F30/F31: headlight lenses are cloudy or cracked, is it worth restoring them?
Surface cloudiness can be removed with wet sanding and polishing, and finally the surface is protected with a UV coating. Deep cracks cannot be removed, and hairline cracks progress through, so then the lens is replaced.
F31: rear right indicator and brake light show a fault, what is wrong?
A pin in the tail light connector is often broken or melted. Most commonly the ground pin (brown wire) burns, because the connectors are undersized. The repair is a new quality connector and replacing or soldering the pins.
F31: the inner lens of the tailgate tail light comes loose, how do you fix it?
The lens is held in place by a plastic locking tab, which often breaks. Gluing and taping hold only temporarily. A lasting solution is a new light with a newer part number, which can be replaced with a 10 mm wrench.