About OpenBMW

OpenBMW is a free, community-maintained technical reference for the BMW I-BUS and K-BUS communication protocols used in E-series vehicles (E31, E38, E39, E46, E53) and the MINI R50.

The goal is simple: make the best-organized, most accurate, freely accessible documentation for anyone working on BMW bus systems — whether you're diagnosing a fault, building an Arduino interface, or deep-diving into NCS Expert coding.

OpenBMW is not affiliated with BMW AG, Siemens, or any OEM. All documentation is community-contributed under open license. Some links are affiliate links — this helps keep the site running at no cost to you.