The new fleet, made of 13 Nova 3 trains, was supposed to be introduced this month.
However, The Scarborough News understands that due to a technical issue this won't be happening until "later this summer".
A spokesperson for TransPennine Express said: “Deliveries of our brand new Nova 3 fleet have now commenced from train manufacturer CAF. A software fault which has now been rectified has delayed the programme by a couple of months which means we now expect customers will begin travelling on these trains from later this summer.”
The company also said that 12 Nova 2 trains and 19 Nova 1 trains will be operating across the network by 2020.
Delay after delay ...
The new fleet was expected to be phased into service this spring following an extension to the original deadline of autumn 2018.
The delay was announced in November last year when TransPennine Express pointed the finger to a technical issue with a key on-board system.
What are the new trains like?
The new Nova 3 trains promise increased capacity and comfort for passengers travelling to and from Scarborough.
They feature 287 seats (106 more than on the existing trains), real-time passenger information system in every coach and Wi-Fi and media servers with power sockets at every pair of seats.
The new fleet will also provide storage for up to four bikes, four toilets and an electronic seat reservations system.
The coaches will be pulled by Class 68 locomotives owned by Beacon Rail and leased from Direct Rail Services.
Once in service, the new trains will operate between Liverpool, Manchester, Huddersfield, Leeds, York, Scarborough and Middlesbrough.