Multiple troubleshooting efforts to address the area of the leak by reseating a seal in the quick disconnect where liquid hydrogen is fed into the rocket did not fix the issue.
Engineers were continuing to gather additional data, said NASA.
Artemis I is a flight test to launch NASA’s Space Launch System rocket and an uncrewed Orion spacecraft around the Moon before the Artemis II mission with astronauts aboard.
Through Artemis missions, NASA will land the first woman and the first person of colour on the Moon, paving the way for a long-term lunar presence and serving as a steppingstone to send astronauts to Mars.
The US space agency on August 30 scrubbed the mission launch for the first time owing to technical glitch with one of the Space Launch System (SLS) rocket’s engines.
Teams saw a hydrogen leak on a component of the tail service mast umbilical quick disconnect, called the purge can, and managed the leak by manually adjusting propellant flow rates.
The Artemis I launch is part of a larger space programme to take astronauts back to the moon sometime after 2025. A first round trip test mission is to take place in about 42 days.