TOKYO—Subaru Corp. has temporarily shut down two factories that account for two-thirds of its global output after finding a problem with power steering on certain models, the latest quality issue to hit the Japanese auto maker.

Subaru on Wednesday said it shut the factories in Gunma prefecture north of Tokyo on Jan. 16 upon discovering the problem, but held off issuing a news release while trying to determine its cause. The company said it expects the shutdown to last until at least Monday.

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