As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DFW - CREW REPORTED LEADING EDGE SLAT ASYMMETRY LIGHT ILLUMINATED AND EICAS MESSAGE ONCE THE FLAPS WERE SET TO 20 DEGREES. EMERGENCY DECLARED FLIGHT LANDED DFW WITHOUT INCIDENT. AIRCRAFT REMOVED FROM SERVICE. AIRCRAFT WAS TAKEN TO AFW FOR FURTHER MAINTENANCE. REPLACED FLAP SLAT ELECTRONICS UNIT AND PROXIMITY SENSOR ELECTRONICS UNIT. SYSTEM GROUND CHECK NORMAL OPERATION.