Defence Minister Wayne Mapp has been told that a long period of inactivity during manufacturing may have contributed to engine faults on the navy's newest ships.
Both HMNZS Otago and HMNZS Wellington experienced engine problems immediately before their deliveries.
The Otago was due to be inspected on Friday afternoon after another fault affecting oil pressure in an engine gearbox.
The latest malfunction happened 24 hours into the $110-million vessel's voyage from Auckland to its home port in Dunedin.
Dr Mapp says contractual problems meant the offshore patrol vessels sat in the water for about 18 months in Melbourne doing very little.
He says the navy has told him that could have led to what he says is a succession of small faults.
The Otago's captain, Lieutenant Commander Simon Rooke, says it's not yet known whether the latest fault also affects the sister ship Wellington.