As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS NOT GROUNDED. FORWARD AVIONICS DOOR INDICATION CAME ON IN FLIGHT. AN EMERGENCY WAS DECLARED AND THE AIRCRAFT RETURNED TO PHL, WHERE IT LANDED SAFELY WITHOUT FURTHER INCIDENT. MAINTENANCE REPLACED PROXIMITY SWITCH (DETECTOR) 36WV AND ACCOMPLISHED A SATISFACTORY OPERATIONAL CHECK, PER AMM 52-71-14.