The company began operations in December 2007
Troubled rail firm Grand Central has been forced to cut the number of trains from the north-east of England to London because of technical problems.
The company introduced a belated daily service from Sunderland, via Teesside and North Yorkshire, last December.
But now it has been forced to reduce operations because of a series of "major component failures".
The company apologised to customers and said contingency plans would be in force until further notice.
A spokesman said: "We have been experiencing some difficulties with our fleet reliability over recent weeks.
"This is in the main, due to a series of major component failures with the power car fleet.
"We are working with those responsible and other repairers to get the necessary work done as soon as is practical in order to improve the current situation.
"Therefore, we have had to take the decision to implement a contingency plan until further notice."
Changes mean some services are cancelled and others starting and terminating in York, with passengers ferried to other destinations by road.
Grand Central trains also stop at Eaglescliffe, Northallerton, Thirsk and York.