As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PDX- ON TAXI OUT FOR FLIGHT 2509, RECEIVED A SPOILER STAB AND RUDDER LIMIT FAULT MESSAGE. FLIGHT RETURNED TO THE GATE. MAINTENANCE DETERMINED MESSAGE WAS DUE TO A ISI AND ADI MISMATCH. PURGED THE PITOT STATIC SYSTEM. NO FAULTS OR MOISTURE FOUND. OPERATIONAL CHECKS GOOD. NO PARTS REPLACED.