As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SEA FLIGHT NR 2378: NR 2 RUD HYD CAUTION LIGHT ON TAXI. AIRCRAFT RETURNED TO GATE. MAINTENANCE C/W DH8-400-SL-27-007A. PERFORMED C/B RESET PROCEDURES. GROUND RAN ENGINES. OPS CHECK GOOD. NO PARTS REPLACED. AIRCRAFT RETURNED TO SERVICE.