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 IAH DUE TO THE FLIGHT CREW REPORTING THAT WHILE CLIMBING OUT A GREEN HYDRAULIC ENGINE #1 PUMP LOW PRESSURE ECAM MESSAGE DISPLAYED. THE AIRCRAFT LANDED SAFELY AT IAH AND TAXIED TO THE GATE UNDER ITS OWN POWER. MAINTENANCE REPLACED THE #1 ENGINE HYDRAULIC PUMP PRESSURE SWITCH AND ACCOMPLISHED A SATISFACTORY LEAK / OPERATIONAL CHECK PER AMM 29-11-17.