As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHEN AIRFRAME DEICE BOOTS ARE SELECTED TO EITHER SLOW, FAST OR MANUAL, THE NR 2 ENGINE INLET BOOT LIGHT FLICKERS ON THEN GOES OUT. THE DEICE PRESSURE CAUTION LIGHT THEN ILLUMINATES. RAN THE CHECKLIST. THE PRESS IS ISO. BOTH SIDES ARE GOOD. MAINTENANCE REMOVED AND REPLACED NR 4 DUAL DISTRIBUTOR VALVE AMM. OPS CHECK GOOD. AIRCRAFT RETURNED TO SERVICE.