BMW E90 light fault warnings even though all lights work
Why does the BMW E90/E91 report a light fault even though all the lights seem to work?
The car replaces a burnt-out parking light dimly with the brake light, so a broken bulb is not easy to see. Check all the tail light bulbs, including the other bulb in the lamp.
What in the tailgate wiring harness causes light warnings on the E91?
On the Touring model the tailgate light wires wear at the rubber boot from the tailgate's movement. Broken wires are spliced and insulated again. The footwell light module can also cut the power to a lamp whose socket has burnt or melted.
What light module fault causes the warnings?
The cause is often poor solder joints in the light module (FRM, in the footwell), and redoing the joints removed the warnings. The alternative is a new or used light module, which is coded to the car.
Does the car report a fault with an LED number plate light?
It may, even though the LED works at the same voltage as an incandescent bulb. Choose a bulb that says CAN-BUS compatible. The warning can also be removed by coding.