The problem with the anti-ice system emerged Tuesday in a flight to Singapore, and the jet returned about an hour later to Haneda airport in Tokyo, JAL spokesman Jian Yang said.
The system is needed depending on weather conditions, and a malfunction can at times be dangerous, but the jet was not at risk and it returned to Haneda safely, he said.
The flight was delayed for six hours, and the passengers were rerouted on another 787, Yang said.
The 787 jets were grounded for four months to confirm their safety after their lithium-ion batteries overheated. The batteries are now encased to prevent overheating from spreading.
Dreamliner batteries overheated on planes that were in flight in Japan and parked in a Boston airport. The jets resumed commercial flights last month at JAL and All Nippon Airways.
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