The action is expected to result in the cancellation or delay of an unspecified number of flights Wednesday, while United performs the checks on a critical equipment upgrade, USA Today reported.
The aircraft are primarily used on long-range flights within the U.S., such as coast-to-coast flights.
"We apologize for any inconvenience for our customers," said United spokeswoman Megan McCarthy. "We are using all available resources to address this issue."
The problem doesn't affect any of the 62 757 jets operated by Continental Airlines, with which United merged last fall. The resulting company was renamed United Continental Holdings (UAL).