The vessel will be replaced on the Poole-Channel Islands route by the Commodore Clipper, while a chartered freight ship, the MV Arrow, will cover for the Clipper on its Portsmouth route.
In a statement, Condor said the Liberation required essential maintenance and would be out of service from Monday until Saturday.
It will then run on two engines between 19 and 24 May to allow the repairs to be completed.
Chief executive Paul Luxon said: ‘We are disappointed that the repair to Liberation is taking longer than anticipated but the additional capacity brought in and our revised schedule is in line with published contingency plans and will maintain passenger and freight services across our network.’
Passengers are being offered a transfer to an alternative sailing where space allows or a full refund. The company said it expected the ‘majority of passengers’ to be accommodated and limited changes to freight services.
The Liberation’s problems started on Monday after the vessel developed problems with one of its engines. The Condor Rapide also broke down this week, stranding hundreds of passengers in St Malo.