Reports from French Polynesia say the Chinese longliner which hit Anuanurunga atoll last month had a malfunctioning radar and used an incomplete map.
The 40-metre-long Ping Tai Rong 49 hit the uninhabited atoll about 720 kilometres south-east of Tahiti while travelling in bad weather at night from the Cook Islands to waters near Pitcairn.
Tahiti-infos said investigators established that the radar had stopped working several days earlier and that the ship hit the atoll at cruising speed.
Ping Tai Rong 49 Photo: FB French High Commission in French Polynesia
The ship is carrying about 120,000 litres of fuel, prompting an immediate despatch of a French navy team to contain a possible oil spill.
There appears to be minimal leakage and the ship remains intact.
The vessel's captain and another crew member are to appear in court in Papeete next month accused of causing marine pollution and breaching navigation protocols.
When the ship hit the reef on 23 July, the Joint Rescue Coordination Centre in Tahiti sent a helicopter to rescue the 15-strong crew and flew them to nearby Nukutepitepi in the Duke of Gloucester Islands.
The Ship is owned by the Ping Tai Rong Ocean Fishery Group.
In March last year, another Chinese fishing vessel ran aground on the reef of Arutua atoll, which is also in the Tuamotus.
The Shen Gang Shun 1, which had shark meat on board while sailing in a shark sanctuary, has been abandoned by its owners.
Attempts to refloat the rusting vessel have been unsuccessful while legal avenues are being pursued to bring them to account.