As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED APU OIL TEMP AMBER MESSAGE WHILE CLIMBING THROUGH FL240 EN ROUTE FROM PHL TO AGS. CREW DIVERTED TO DCA BECAUSE NR 1 GENERATOR WAS DEFERRED AND LANDED WITHOUT INCIDENT. MAINTENANCE TROUBLESHOT APU AND PERFORMED CHECKS USING AIRCRAFT MAINTENANCE MANUALS. NO DEFECTS FOUND. AIRCRAFT WAS RELEASED FOR SERVICE.