Maritime New Zealand has given the Interisland ferry, Aratere, approval to resume services late on Friday night after it passed safety tests carried out in Wellington harbour.
A rail freight only sailing will leave Wellington at about 11.30pm, and freight only sailings will operate on Saturday. It is anticipated passenger services will resume on Tuesday.
The ferry was piloted at full speed around the harbour on Friday in an attempt to establish what caused its repeated engine problems.
Technical experts were attempting to simulate what happened on Monday night with the vessel at full speed.
The Aratere lost power in Tory Channel that day and then had a crank case explosion while on sea trials on Wednesday.