031781는 BMW 결함 메모리에 저장된 코드입니다（ISTA 결함 코드, 표준 OBD-II P 코드 아님）。
코드 의미: 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.
