21924 är ett fel som lagrats i din BMW:s minne (en ISTA-felkod, inte en standard OBD-II P-kod).
Vad det betyder: Flexray, external cause (group error) — transfer case (LMV, xDrive). This is a secondary/knock-on Flexray-bus entry, not the root cause: the module logged a fault whose source is in another node. On forums it often cleared after transfer-case/gearbox service (fluid change). Usually not serious by itself — fix the root cause if there are symptoms.
