As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT IN BASE MAINTENANCE: AN EMERGENCY WAS DECLARED AND THE AIRCRAFT RETURNED TO PHL DUE TO THE FLIGHT CREW REPORTING AN #1ENGINE ANTI-ICE FAULT. THE AIRCRAFT LANDED SAFELY AT PHL WITHOUT FURTHER INCIDENT. MAINTENANCE REPLACED THE #1 ENGINE AFT AIR-INTAKE ANTI-ICE VALVE AND ACCOMPLISHED A SATISFACTORY OPERATIONAL CHECK PER AMM 30-21-51.