Auto dimming rear view mirror

[christopher j 10]

Hi guys.

Have had my 2008 130i for just under a month now and am wondering how long it takes for the auto dimming interior rear view mirror to darken up. Should it be dark generally at night with cars behind?

I have noticed it slightly darker than usual sometimes but not all.

I have had Continental in Takapuna check it over and they seem to think it's working. Have also checked all fuses and all seem to be fine. Have tried shining a torch at the rear facing sensor as well which didn't really do anything.

[Michael. 2313]

They are constantly variable I've found.

Theres usually a front sensor that detects darkness, might be on the glass of the window, or the back of the mirror.

Cover that and then try get a bright light on the inside sensor. It might darken automatically anyway, as the ambient light vs covered night sensor would trigger it.