The tunnel will be closed between 11pm and 5am from Tuesday, May 28, to Thursday, May 30.
The tunnel will open on the hour to clear the queued traffic.
Motorists will still be able to travel between Lyttelton and Christchurch via Cashmere along Dyers Pass Rd, or via Sumner along Evans Pass Rd and Sumner Rd.
NZ Transport Agency Waka Kotahi maintenance contract manager Steve Rusbatch said the tunnel's fire protection system, which has water sprinklers evenly spread along the tunnel, was installed in 2019.
The system gets a full check up every two years.
Rusbatch said traffic volumes are very low at this time of night and the last bus at 11pm won’t be affected by the closure.
He said traffic will be able to pass through the tunnel on the hour and emergency vehicles will not be affected by the closure.
"Thank you for your patience and understanding while these essential works take place."
