As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
TAKEOFF WARNING HORN SOUNDED DURING TAKEOFF ROLL AT 30 KNOTS. ABORTED TAKEOFF AND RETURNED TO GATE. HORN WAS SILENCED AFTER SPOILERS WERE CYCLED. MAINTENANCE PERFORMED TAKEOFF WARNING SYSTEM TEST PER MAINTENANCE MANUAL 27-00, CODE 4, PG 215, SYSTEM CHECKED NORMAL. DISCREPANCY COULD NOT BE DUPLICATED.