What was found
AIRCRAFT WAS NOT GROUNDED: AN EMERGENCY WAS DECLARED AND THE AIRCRAFT RETURNED TO PHX DUE TO THE FLIGHT CREW REPORTING A YELLOW HYDRAULIC ENGINE 2 PUMP LOW PRESSURE MESSAGE. THE AIRCRAFT LANDED SAFELY AT PHX AND TAXIED TO THE GATE UNDER ITS OWN POWER. MAINTENANCE FOUND THE ENGINE PUMP PRESSURE SWITCH LEAKING DUE TO O-RING BEING BLOWN OUT. MAINTENANCE REPLACED THE PRESSURE SWITCH PER AMM 29-13-17. A SATISFACTORY LEAK / OPERATIONAL CHECK WAS ACCOMPLISHED WITH NO ISSUES NOTED.