The service has said three trains on the Airport to South Hylton line were operating with delays, with a gap of up to 20 minutes, while services to South Shields have also been affected.
Tickets were accepted on Go North East buses and a taxi service was put on between Regent Centre and Airport as the network began its working day facing the issues.
A spokesperson for the network said: “The track circuit fault at the depot has now been repaired.
"We currently have delays to service between South Hylton and Airport in both directions.”
This Sunday, April 25, no trains will run between Airport and Regent Centre due to track work, with the 900 replacement bus service to run.