How accurate is the brakepad wear sensor?

[drvai]

Hi to everyone. Hope you all are having a great Holiday weekend.
I have a question... How accurate is the brake pad wear sensor? Im refering to the
one in the iDrive system. This is based on an actual physical sensor or it
estimates depending on milage?

[mastek]

The one on the iDrive is a timer based on mileage - does not have a sensor.
However, the car features 3 brake pad wear sensors that simply read metal contact when the pads are worn down, that enables a warning on the dashboard (i dont think its in the iDrive).

[arter]

The brake wear system has two parts. One is a sensor on the brake pad to will go off when the pad is down to ~ 3 mm left. there are three of them, 2 on both front tires and one on one of the rears.

The other half of the system is the count down which estimates the life remaining until the sensor goes off. This counts the number and length of the braking events to estimate life.

Since I track my cars and have gone through a set of race pads already, the idrive indicator has me at needing new pads ( car is at 9,000 miles) , which makes the dealer look at the stock pads each time ( and they are still at 11 mm - new is 14?).

[drvai]

Thank you so much. So there are 3 levels of warning? Or just one warning stating you have 3mm left?

[arter]

The iDrive does a count down of estimated mileage left.

The sensor does nothing until it wears down enough to short and trigger a warning light.