brake sensor question

[BMW330xi]

If you do not install the brake sensor, does the light remain on or would it reset after 2 minutes and never get warned again?

My 2006 E90 330xi has 85k miles, and front-pad never needed to get replaced but my rear pads have been replaced during the warranty (not because the brake pad light came on).

Do you know if BMW's pad squeal when worn down? I have iDrive but the front-pad miles just never seem to go down. I drive a lot of highway miles.

I am wondering if the brake pad sensor is there at all...

[BMW330xi]

how many miles to do before brake pad needs to be replaced?

From what I read it seems only to light up if the brake sensor is broken (grinds away to expose the connection), so does the car have any other logic when calculating how much brake time is used at what speed?

[frogman57]

The brake wear displays (seperate for front and back) also are an menu item service info that appears on the dash computer of non iDrive equipped units. Accessing of that menu is by means of the up down button on the stalk (and sometimes the pushbutton). Rather arcane until you get the hang of it.

The car's computer rates your driving by integrating accelerations, average speed, etc, and knows if you are doing a lot of stop and go or highway driving. I know for a fact that it recalculates service interval (mine was shown as required at under 14K mi - stop and go) and I am 99% sure it is used in the a calculation of a brake wear estimate.

You do not think a warning light until you cut the sensor in the pad. On the E46, this was with 1 mm of pad left. The E46 just gave you a light with no indication of front or back. The dash warning on the E90/92 doesn't either, but the service info could give you a clue without taking wheels off.

The sensor is cut and has to be replaced. I am not not sure how you get the light off on the E90, but I bet you dollars to donuts (if the donuts have sprinkles) you can do it with the stalk.

[BMW330xi]

or you did it based on its miles remaining estimate and saved yourself a sensor which is like $15?

is the labor meaningfully cheaper if you replace the pad before the sensor is cut?

[frogman57]

They are only like $15.