Engineers will make repairs to a steel plate between the swing-span and the deck.
The closure will be from 8pm on Tuesday until 5.30am on Wednesday.
Motorists can use detours that will be signposted on State Highways 2 and 26.
The Kopu Bridge was closed temporarily due to a structural problem in July, causing major traffic delays on State Highway 25.
A new bridge being built alongside is not due to open until mid-2012.
