As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED APU OIL PRESSURE CAUTION MESSAGE IN FLIGHT EN ROUTE FROM DCA TO BNA. CREW DIVERTED TO CLT AND LANDED WITHOUT INCIDENT. MAINTENANCE INSPECTED THE APU, SERVICED THE APU OIL LEVEL AND PERFORMED CHECKS USING THE AIRCRAFT MAINTENANCE MANUAL. AIRCRAFT WAS RELEASED FOR SERVICE.