Hi,

have you checked the "LEDs" in the Steering Electronic? They are named with the typical Problems where you can get an better Diagnostic, like "Endstufe" or "Leistungskreis" please check that too. Did you check the "Dioden-Modul" it is located in LE and JE Models on the left Side of the Masterbrakecylinder. You can open that Modul and there are only 2 Diodes in. Check them with an Tester.

Mfg

Sven