BMWeb documentation

Getting connected

The app talks to the cable through Web Serial, which only Chrome and Edge on a computer have. Safari and Firefox do not, so on a Mac use Chrome or Edge.

1. Plug the cable in directly, into the car's diagnostic port and into the computer. Avoid USB hubs.
2. Click the cable chip in the top bar. The browser only opens its port picker after a click, so the first connect is always yours.
3. Choose your port. On macOS it starts with cu.usbserial, cu.usbmodem, cu.SLAB or cu.wchusbserial; on Linux, ttyUSB or ttyACM. The browser remembers it, and the app reopens the cable on every load after that.
4. Pick the car, then a module. Each chassis lists its modules by system. Opening one brings up the module's own menu, with the F-keys along the bottom.

Settings

Settings switches between the classic text layout and a modern one with the same keys and screens, picks one of six skins, shows English or BMW's original job names, and decides whether activations ask first.

The cable

One kind is supported: the standard K+DCAN USB cable. An ELM327 is not it. The app sets the line up for each module by itself:

FTDI latency

If your cable has an FTDI chip, set its latency timer to 1 ms. The app cannot change it; it tells you when the symptoms look like a slow timer. On macOS the driver's default can be high enough that the cable misses its own echo, which shows as IFH-0003.

Where it works

On the car

Every module screen is BMW's own INPA screen, decompiled and drawn as the dealer tool drew it. A module BMW never drew a screen for says so instead of guessing.

Without a car

The reference material from the dealer software, in the Apps hub. None of it needs a cable.

Flashing, tuning and logging

One app in the hub for the Siemens MS45 engine computer and the GS20 automatic gearbox. It is a beta and says so before it opens.

Flashing

Checksums are corrected for you, and every write is logged in the module's own programming history, as the dealer tool does.

Tuning

Open a firmware image with an XDF definition and edit named constants and tables in real units, with the raw hex beside them. Tables can be set, scaled, interpolated and smoothed, and shown as a 2D graph or a 3D surface. Comfort mode lists the common MS45 values under plain names. Saving writes a file on your computer, never the car.

Live tuning

On an MS45 running the live-tune program, LIVE ON puts every edit onto the running engine as you make it, and a live cursor marks the cells the engine is reading. Beside the editor you can open the fault memory, the learned adaptations (each clearable on its own), a rev gauge and live values. Tick Save to ECU and the DME keeps the tune at key-off.

Logging

Comfort lists the readings that matter under plain names; Expert offers every read-only job of every module. Each reading gets a chart while you drive, and runs are kept in History and export as CSV. A replay scrubs through a run, and Map mode paints the path the engine took across a table from your tune. A DME reset during a run is kept as a black box.

Supported cars

How much each chassis covers depends on how many modules it has: an E65 carries 96 module definitions, an E60 91, an E90 61, an E46 55, an F30 19. A parts lookup needs no car, so it reaches far beyond the diagnostics.

Writing and safety

Reading is open. Anything that changes the car asks first, and a refused write sends nothing at all.

Every job is checked before it runs

A job the app does not recognise is treated as a write, not as safe, and a blocked write is stopped before a single byte reaches the car. A permanent write (an EEPROM change, a service reset) always asks, whatever the setting. In a remote session, the car's owner approves each write.

Activations

Activations ask first by default and say which kind they are: a test that holds until you change it back or leave the screen, or a permanent write that stays. Leaving an activation screen releases anything still held.

Coding

A coding write is an EEPROM write, and on a module that controls the immobiliser or the airbags a mistake can stop the car starting. So every coding write:

1. lists every change and waits for you to choose Write to car;
2. is refused unless the app has proved which variant and coding index the module is;
3. saves the module's current coding before anything is sent;
4. re-reads the module afterwards and reports any byte that did not land.

Your changes are laid over what was just read from the module, never over a blank image. Modules that are coded in numbered blocks rather than by address are refused for now.

Flashing

Working offline

The app installs to the home screen or the dock and keeps working without a connection. Everything it reads is a static file, so once it is cached there is no server to be unreachable.

For a copy that never touches the network, every release has self-contained builds: unzip one and open index.html.

Troubleshooting

The errors people actually hit, and what each one means.

Limitations

• Flashing covers two modules: the MS45 DME and the GS20 gearbox. Other modules can be read and coded, not flashed.
• Coding refuses block-coded modules, such as the E46 body module (GM5) and light module (LSZ), until the way the factory tool addresses their blocks is confirmed.
• A phone cannot use the cable. Everything that needs no car still works there.
• If the wrong coding keyword table is matched, it returns plausible but wrong keywords instead of failing loudly. Treat unexpected coding readouts with suspicion.