I've read in the manual that it's possible to check on a stored error code via the dash-the tach display, I think. These seem to be BMW specific error codes, not some generic obdc codes. Can anyone verify this, and maybe point to a link of the BMW codes?

 

It's on page 56, see 'check control messages'.
Here is a quick cut and paste.

1. Briefly press the button in the turn indicator
lever repeatedly until "SET/INFO" is displayed.
2. Press and hold the button until the display
changes.
3. Press the button repeatedly until the display
shows the corresponding symbol and
"CHECK INFO".
4. Hold the button down.
"CHECK OK" appears if there are no Check
Control messages.
If a Check Controlmessage has been stored,
the corresponding message is displayed.
5. Briefly press the button to check for other
messages.