All Nippon Airways and Japan Airlines are checking their Boeing 787 fleets for wiring problems unrelated to battery defects that plagued the aircraft earlier this year.
ANA said Wednesday the departure of a 787 plane was delayed over problem wiring for a system to put out engine fires.
ANA, which has 20 Boeing 787 jets, said the flight from Tokyo to Frankfurt departed after the part was exchanged.
Spokeswoman Masumi Oguchi says ANA found two similar problems while inspecting its other 787 Dreamliners.
Japan Airlines says a 787 headed to Helsinki returned for inspections, and its nine other 787s are being checked.
Dreamliner jets were grounded worldwide in January for lithium-ion batteries that overheated or caught fire. Flights resumed four months later after a revamped battery system was installed.