BMW E90 xenon headlight levelling and swaying
Why do the E90's xenon lights sway up and down?
The most common cause is the wiring of the rear axle height sensor. The wires have chafed or broken, for example at the inner wheel arch liner or where they enter the body at the left rear. Check the wiring before replacing the sensor.
How do you check the automatic levelling?
Do not adjust the lights by hand until the automatic levelling has been verified. Disconnect the levelling rod of the left rear lower control arm and move it through its full travel. If the lights move with it, the automatic levelling works.
How do you adjust the xenon height by hand?
Each side has its own adjusting screw. The adjustment is done with the car a few metres from a wall. After adjusting, make sure the light does not dazzle oncoming drivers, since the adjustment easily ends up pointing too high.
Is a wider beam at low speed a fault?
No, if the car is an EU model with AHL2 lights. They have a town light function, which widens the beam below 50 km/h. Above 50 km/h the lights return to centre.