[starboard]

I bought a 2011 328i 3 months ago. The rear brake readout was very good, over 15,000. But now, after 1000 miles, it says I need new rear brakes with only 700 miles left. What happened? Dealer says their records show an incomplete recording, that they read off the key fob and they have nothing from that now. I saw the readings directly on the i drive screen during purchase. Can readings be easily changed upwards, at will, with old worn brakes? Or might the i drive 700 mile reading be in error?

How accurate are these sensors? Is there a way to track all changes made to the readouts?

[vomba]

Brake wear indication is quite strange on my F11 530 XD MY 2012, too. I changed rear brake pads in 2017. From then on, indicator first went down from 31000 to 3100; afterwards it stopped and later even began to count upwards. Afaik you cannot manipulate it; but it seems that firstly it counts down depending on which brake usage the car has experienced in the past. When it reaches the point where the pad should indicate it is time to change, it stops or even counts upwards again, waiting for the signal of the indicator wire in the pad.
In your case the opposite may have occured; the car "thought" by experience that the pads would still last; but then the indicator wire became active.
Not a very useful feature; but whatsoever. Ignore the mileage indication until it says that you must change brake pads within a few 100 km; that's what I do.

Vomba

[dls]

CBS (condition base service) indicators can be reset or rolled back from BMW diagnostics software like ISTA or Rheingold.

Brake fluid CBS value is based on time, and not on any kind of condition of brakes.
Brake pad wear sensors are three-state devices that are incapable of exact measurement. Three states are:
1. New sensor, both wires connected. This is the only state in which the brake pad status can be reset.
2. Sensor with wear. One wire remaining. Cannot reset brake pad status.
3. Sensor past maximum wear. No wires remaining (this causes Brake symbol on dash).

[starboard]

Went to a well regarded independent mechanic and had him do a quick brake inspection. With a mirror and flashlight he easily determined I have about 20,000 or more miles left on all 4 brakes. Today the idrive is telling me time for service NOW. The BRAKE warning light above the steering column won't shut off.

Is there a way to disable this until I get new brakes? Without spending a trunkload of cash?

[dls]

I have no idea how could anyone convert brake thickness to miles - this heavily depends on driving style and even material of brake pads, but the DSC/DXC module would not allow you to reset the brake mileage until you connect the new brake sensors. You don't have to install them - just temporary connect them instead of the old ones. They cost less than $20 bucks a piece, you need two - one front, one rear.

[starboard]

It would certainly be easy enough to estimate that the brakes had closer to 20,000 miles left vs the 400 miles the car was saying. It was a guestimate to establish they did NOT need immediate replacement. That was not the point of the question. Thank you

[nsjames]

Originally Posted by starboard

It would certainly be easy enough to estimate that the brakes had closer to 20,000 miles left vs the 400 miles the car was saying. It was a guestimate to establish they did NOT need immediate replacement. That was not the point of the question. Thank you

what the man was saying is that people estimating miles is exactly like the CBS readings that have alarmed you. Get actual pad measurements in MM.

chances are a pad wear sensor is damaged.

[mjn77]

Have you actually checked the sensor and cable?

I had something similar and the cable had worn against the wheel and cut through the cable.