D91DFD is a fault stored in your BMW's memory (an ISTA fault code, not a standard OBD-II P-code).
What it means: Missing 'status, exterior lights, front electronics 2, right' message — receiver FRM/body module, transmitter LHMR (right headlight module). A loss of communication with the right front lighting; typical causes are connector corrosion/moisture or a faulty headlight module.
