Vessel had been using just three after a control system fault
The Steam Packet Company has confirmed the Manannan is now running on all four engines.
The fastcraft had been using just three of its engines after a problem was detected with the control system in one engine over the weekend.
It meant passengers had been facing longer than usual crossing times over the last few days.
The vessel is now expected to run to schedule on its two round trips to Liverpool today.
Isle of Man bans personal meat and dairy imports from EU to prevent spread of disease
Government introduces stricter biosecurity measures to protect livestock following European outbreaks of foot-and-mouth
Locum breast radiologist secured by Manx Care
Clinics to be reinstated from next week
Tynwald Youth Committee to look at 'support for life after school'
Group formed of seven Island residents, aged between 15 and 24
Richmond Hill closed after road traffic collision
UPDATE - The road has now reopened