What was found
(CAN) DURING APPROACH , THE NOSE GEAR FAILED TO EXTEND , THE CREW CARRIED OUT ALTERNATE GEAR EXTENSION AND A/C LANDED SAFELY . DURING THE SAME FLIGHT , AFTER TAKEOFF(ABOUT 5 MINUTES) THE LANDING GEAR CAUTION LIGHT CAME ON AND WENT OUT AFTER ONE MINUTE. MAINTENANCE CREW FOUND ERRONIOUS FAULT CODES ON THE PSEU( PROXIMITY SENSING ELECTRONIC UNIT ) AND REPLACED THE UNIT . SEVERAL GEAR RETRACTIONS CARRIED OUT ON JACKS AND THE FAULTS COULD NOT BE DUPLICATED.