The internal ramp inside the Commodore Clipper has prevented 25 passengers from removing their vehicles.
Some freight destined for shops in Jersey is on board the ferry.
The fault was discovered shortly after departing from Portsmouth on 23 December.
Condor Ferries have provided all affected passengers with hire cars.
A spokesperson for the company says repairs will take place to get the clipper back in service on 27 December, its next sailing date.