031781 is a fault stored in your BMW's memory (an ISTA fault code, not a standard OBD-II P-code).
What it means: Head unit (HU-H) — Real-Time Traffic Information (RTTI) functionally limited. This is NOT a faulty part: it's an ambient/back-end issue (temporary loss of the traffic-data connection or a back-end restriction). Replacing components won't help — it clears itself once the service/connection is back. Informational, nothing to worry about.
