The southbound tunnel will be closed from 10pm each evening until 4am. Traffic will be diverted off the Northern Gateway Toll Road at Waiwera and back onto the state highway again at Silverdale.
This will add approximately 10 minutes to the journey.
The closures have been timed to coincide with the lightest traffic volumes to minimise the disruption to drivers.
The work is necessary to ensure signs which provide important safety and travel information to motorists are well maintained.