Kyran Winterburn nearly doubled the lead towards the end of the match, forcing the Onehunga keeper into a fine save, and Fletcher fired into the side netting from an acute angle but Northland could not land the killer blow which set up a tense finale.
The clean sheet and three points would be heading back up north though, leaving Northland FC's chances of survival in their own hands with two games left.
Head coach Dan Johnston said: "We were aware of the aerial threat they posed in the final third and at set-pieces so we talked about winning those headers and the second ball. All this means though is that we don't need to rely on favours from other clubs, if we are going to see this through we need to apply ourselves in the same manner over the next two games."
Northland have a rescheduled match against Bucklands Beach next week, who have already been promoted, before hosting Te Atatu, now in the bottom two, on the final day of the season.