As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 1231 - EWR - CREW REPORTED SPS ADV MESSAGE ON EICAS IN CRUISE. CREW PERFORMED AIR RETURN AND LANDED UNEVENTFULLY. EWR MX REMOVED AND REPLACED ANGLE OF ATTACK SENSORS AND PERFORMED OPERATIONAL CHECK SUCCESSFULLY. AIRCRAFT WAS APPROVED TO RETURN TO SERVICE.