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 DUE TO: WHILE IN CRUISE ENG 1 HYDRAULIC PUMP LOW PRESSURE LIGHT FLICKERED. FOUND HYDRAULIC SYSTEM A QUANTITY AT 40% AND DROPPING, SYSTEM QUANTITY DROPPED AS LOW AS 0% THEN ROSE TO 13% SHORTLY AFTER RUNNING CHECKLIST; AIRCRAFT DIVERTED TO AND LANDED SAFELY AT ORD. (OPEN).