As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
BOI - "SPRL OUTBD" CAUTION ILLUMINATED WITH NO ABNORMAL INDICATIONS ON PFCS. CAUTION EXTINGUISHED 10 MIN LATER. DIVERTED TO BOI. LANDING UNEVENTFUL. REMOVED AND REPLACED FLIGHT CONTROL ELECTRONIC CONTROL UNIT IAW 27-00-01-000/400-802. REPLACED AS A PRECAUTIONARY MEASURE. ALL OPS AND INDICATIONS NORMAL. RETURNED TO SERVICE.