Assuming the pads aren't worn, sometimes the brade pad indicators can wear out or the wiring can become frayed/contaminated with road salt, sand, dirt, etc... All depending on how old they are and if they were routed properly upon re-installation. They're so cheap most of us change them out with new indicators when we change our brakes. But most non-BMW specific shops just re-use them as well as if a DIY'er is on a tight budget. Nothing wrong with re-using them, but they'll wear out eventually and the signal will falter which can also throw the fault code.
But it's always good to check the pads closely (both sides of each caliper) before assuming you just have a faulty sensor. Our cars are getting up there in age and the calipers can start sticking which can burn through a set of pads pretty quickly. |