Flight NZ81 was two-and-a-half hours into the flight, and to the West of New Caledonia, when it changed direction, on Thursday afternoon.
Air New Zealand safety officer Captain David Morgan said the decision to turn the plane around was made so one of the engines could be checked.
"The aircraft requires the anti-ice function inside one of its engines to be checked by our maintenance team and doing so in Auckland rather than Hong Kong will ensure the aircraft can return to service much faster."
There was no safety risk to passengers, Morgan said.
Those affected would be put on the next available flight.
RNZ
