As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: AN EMERGENCY WAS DECLARED AND THE AIRCRAFT RETURNED TO DFW DUE THE FLIGHT CREW REPORTING A YELLOW HYDRAULIC RESERVOIR LOW LEVEL MESSAGE. THE AIRCRAFT LANDED SAFELY AT DFW AND TAXIED TO THE GATE UNDER ITS OWN POWER. MAINTENANCE FOUND THE YELLOW HYDRAULIC SYSTEM RESERVOIR WAS ACTUALLY OVERSERVICED AND DRAINED THE SYSTEM TO THE CORRECT LEVEL. A SATISFACTORY LEAK/ OPERATIONAL CHECK WAS ACCOMPLISHED WITH NO DEFECTS NOTED.