NEW YORK (Reuters) - United Airlines has found a wiring problem on one of its Boeing Co 787 jets, an issue that affects the same system that caused a fire aboard a Japan Airlines Co 787 in Boston on Monday, the Wall Street Journal reported, citing a source.

The airline found improperly installed wiring in electrical components associated with the auxilliary power unit, the Journal reported. United examined the components after the fire on Monday, which took the Japan Airlines jet out of service.

United spokeswoman Christen David said United inspected its 787s after the Boston incident, but she declined to confirm the Journal report or to discuss the results of the inspections.

(Reporting by Alwyn Scott; Editing by Bernard Orr)