What was found
AFTER GEAR RETRACTION, LG WOW SYS FAIL MESSAGE APPEARED. THE QRH INSTRUCTS THE PILOT TO LAND AT THE NEAREST SUITABLE AIRPORT. RETURNED TO HNL. UPON GEAR EXTENSION THE MESSAGE WENT AWAY. MAINTENANCE CLEANED THE PROX SENSOR FOR THE NLG. THE ISSUE REAPPEARED 4/3/09, FLIGHT NUMBER 159, SAME CIRCUMSTANCES, AND THE CREW DECLARED AN EMERGENCY. MAINTENANCE SERVICED THE NLG STRUT IAW EMB MM 12-12-09-03.