The presidents of the two African nations sealed deals in September for a demilitarized zone between their borders and other security agreements that would allow the oil exports to resume.
South Sudan exports its oil through Sudan's pipelines, but those exports have been halted since early 2012. Sudan gets a cut of the exports' revenue.
Tuesday's meeting in Ethiopia ended without agreement on implementing September's deals.
African Union mediator and former South African president Thabo Mbeki says the two sides would meet again on the issue in January.
The leaders of Sudan and South Sudan also are scheduled to meet during a January summit in Ethiopia.