As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DIVERSION / DECLARED EMERGENCY. THIRTY MINUTES OUT OF BOSTON SYS B HYDRAULIC QUANTITY RAN DOWN TO ZERO, SHORTLY AFTER SYS B ENGINE PUMP WENT LOW PRESSURE. PER MX REQUEST TURNED OFF ELECTRIC PUMP. REMOVED AND REPLACED B-SYSTEM ELECTRIC PUMP PER MM.