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 TYS TO PHL. CREW FOLLOWED QRH, DIVERTED TO TRI AND LANDED WITHOUT INCIDENT. MAINTENANCE INSPECTED APU, CLEANED APU OIL PRESSURE SWITCH CONNECTOR AND PERFORMED CHECKS USING AIRCRAFT MAINTENANCE MANUALS. AIRCRAFT RELEASED FOR SERVICE.