Do you have a 2nd level scanner that will scan all modules?

A prime suspect is the ignition switch. The car will turn off the headlights when you turn from 2 to 1 position. Not sure how the car would stay running unless there are parallel circuits. I would do some fiddling with the key switch in the on position and see if you can get the lights to blink out also see if the fog lights will run if the low beams don't.

If there was a momentary loss of power to "T15" or whatever BMW calls the power from position 2 (on position) it would give you the symptom you described you could try it. Turn the key from 2 to 1 to 2 quick as you can I'm betting engine stays running and headlights will go out. The difference is I think you said the lights didn't come back on when you turned the switch off and on but it wouldn't surprise me if you had to turn the key to zero position to reset the light control module

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)