It seems to be impossible to turn off the internal M8 coprocessor for step counting if you are using a wristband. You can rearrange the sources in Health.app: I tried this, but the internal M8 coprocessor is still counting steps. Also the counting is now mixed with the data of the internal M8 coprocessor plus the data of the wristband. And you can only disable the wristband in sources, but not the the internal M8 coprocessor In this Apple Discussion Board Thread they are describing the same issue: https://discussions.apple.com/message/26877591 i also found this in a description of a Health.app sync app for FitBit (Sync Solver). They write that it isn't possible to disable the internal M8 coprocessor, you can prioritization of the sources and that this should avoid double counting, but they write "SHOULD" Anyone else there outside with this issues?