What was found
ON DESCENT INTO PHX EN ROUTE FROM AUS, AFTER LANDING GEAR EXTENDED, RECEIVED AN INTERMITTENT HORN AND FLASHING UNSAFE NOSE GEAR LIGHT. PROBLEM OCCURRED AFTER BOTH NORMAL AND MANUAL GEAR EXTENSIONS, AS A PRECAUTION REQUESTED EMERGENCY EQUIPMENT STANDBY. MAINTENANCE REMOVED AND REPLACED NOSE LANDING GEAR DOWN LOCK SENSOR S846 IAW BMM 32-61-41-4, OPERATIONAL CHECK WAS GOOD.