OpenDS2

Open-source BMW diagnostics for the Mac. Plug a K+DCAN cable into your E-series BMW, read and clear fault codes, watch live data, and see how every module is coded, all in a native Mac app.

OpenDS2 is named after DS2, the diagnostic protocol BMW used over the K-line on E-series cars. It runs on EdiabasLib, an open-source implementation of BMW's EDIABAS.

Status: early. It's developed and tested on an E46 (2003 M3). Other E-series cars should work for reading, but haven't been tested yet. See Supported cars. If you have another chassis, a read-out of your car is the most useful thing you can contribute.

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What it does

• Scan the car and list every module that answers
• Faults: read and clear fault memory, translated into English
• Live values: every sensor and status value a module reports, in metric or imperial
• Info: part numbers, software versions and coding index for each module
• Coding: see how each module is coded. With NCS data it decodes into named options
• Actions: the module's own tests and resets (service reset, activations, DSC bleed…)
• History: save a read and compare it with a later one
• AI assistant (optional): a local MCP server so Claude or another assistant can work on the car with you. Coding changes it suggests wait for your approval.

Changing coding is limited to a few modules that have been verified on a real car (see Safety). Everything else is read-only.

What you need

1. A Mac with macOS 14 (Sonoma) or newer, Apple Silicon or Intel.
2. A K+DCAN USB cable (the common "INPA K+DCAN" cable with an FTDI chip). Cars older than about 2007 need the cable's switch set to the position that bridges pins 7 and 8.
3. BMW's ECU description files (the Ecu folder of .prg and .grp files). These are BMW's files, so OpenDS2 doesn't include them. They come with BMW Standard Tools / EDIABAS, usually in C:\EDIABAS\Ecu. Copy that folder to your Mac.
4. Optional: NCS Expert coding data (DATEN folder for your chassis, e.g. DATEN\E46). This is only needed to decode coding into named options.

Install

1. Download OpenDS2.zip from the latest release.
2. Unzip it and drag OpenDS2.app into Applications.
3. If macOS says it can't check the app for malware, open Terminal and run:

   xattr -dr com.apple.quarantine /Applications/OpenDS2.app

   (The app shows this command too if macOS blocks it.)

The app checks for updates itself (Setup → App updates).

Use it

1. Connect: plug the cable into the car's OBD port and your Mac. Ignition on (position 2, dash lit). The engine can be off.
2. Open Setup (first launch opens it for you):
   • ECU description files: pick your Ecu folder.
   • Connection: pick the cable's port (cu.usbserial-…). If the list is empty, your cable needs a driver.
   • Modules: E-series (K-line) for cars up to about 2007; D-CAN / F-series for E8x/E9x and later.
   • Optional: Coding data: pick your chassis's NCS DATEN folder.
3. Scan. The first full scan takes about a minute. After that, quick scans only check the modules your car has.
4. Click a module to see its faults, live values, info and coding. Read all reads every module and saves a report.

Tips

• Only one program can use the cable at a time. Close INPA, ISTA and other apps first.
• Keep the battery healthy (a charger is ideal for long sessions). Low voltage causes odd errors.
• If a module doesn't answer, check the ignition and the cable switch, then Scan again.
• Units: Setup → Units switches between metric and imperial.

Using it with Claude (optional)

Turn on Setup → MCP server and click Copy to get the claude mcp add … command. The assistant can then do anything the app's buttons can: scan, read modules, explain faults, clear faults, run tests and resets.

Coding is different. When the assistant wants to change a coding option, the app shows you the change (option, old → new value, exact bytes) and waits. Nothing is written until you click Write to car. Programming, the odometer and the immobilizer are off-limits to everyone, including the assistant.

Supported cars

Chassis	Reading	Coding changes
E46 (3 Series, 1998–2006)	✅ tested (M3)	Body module (ZKE5/GM5) ✅ · DSC MK60 ✅ · Cluster VIN ⚠️ experimental, not working yet
E36, E38, E39, E53, E83, E85, E52	should work, untested	read-only
E8x / E9x / E6x (D-CAN)	partial, untested	read-only
F / G series (ENET)	not yet	—

Some screens are made for one engine: Dashboard, Misfires, VANOS and Tests are for the E46 M3's S54 (MSS54) for now. Help adding other engines is welcome. See AGENTS.md.

Safety

This software talks to a real car. Reading is harmless. Writing is rare, narrow and guarded:

• A coding change is one option at a time, on a module verified on a real car. It needs the engine off and the battery ≥ 12 V. The app saves a backup first, then shows you the exact byte change to confirm, and reads it back afterwards to check it took.
• Coding changes only run on the chassis they were verified on (only the E46, so far). On any other car the app is read-only, even if it shares a module with the E46.
• Programming/flashing, immobilizer and key data, and the odometer are never touched. There is no odometer function in this project.
• The cluster VIN write exists only to align a swapped instrument cluster with the car it's now in. It refuses unless the cluster's VIN differs from the car's own, and it only accepts the car's VIN. It does not work yet and is off by default. See docs/CLUSTER-VIN-FIX.md.

Use at your own risk. There is no warranty (see LICENSE).

Build from source

You need the Xcode Command Line Tools (xcode-select --install), Microsoft's .NET 10 SDK installed to ~/.dotnet, and EdiabasLib:

git clone https://github.com/ecrawshaw/opends2.git
cd opends2
git clone https://github.com/uholeschak/ediabaslib.git   # used as-is, not modified
./tools/check.sh    # offline checks, no car needed: must end with "failed: 0"
./build-app.sh      # → dist/OpenDS2.app and dist/OpenDS2.zip

To get started on the code, read AGENTS.md. It covers the layout, the safety rules and how to add support for another chassis.

Contributing

• Have a car other than an E46? Follow docs/VEHICLE-READOUT.md (read-only) and open an issue. Remove your VIN before posting anything publicly.
• Bugs and ideas: open an issue with the module, what you clicked and the error text.
• Code: see AGENTS.md and CONTRIBUTING.md.

License

GPLv3. See LICENSE and NOTICE.md. OpenDS2 is built on EdiabasLib by Ulrich Holeschak (GPLv3).

OpenDS2 is an independent project. It is not affiliated with, endorsed by or connected to BMW AG. BMW and the names of BMW models are trademarks of BMW AG, used here only to say which cars the software works with.