American Honda Motor Co. is issuing two separate Honda Odyssey minivan recalls — covering more than 641,000 vehicles — to address defects that can result in passenger seats moving unexpectedly, according to the National Highway Traffic Safety Administration.

The larger of the two recalls covers 633,753 Odyssey minivans in the 2011 to 2016 model years. These vehicles have second-row outboard seats with a release lever that allows the seats to move for easier access to the third row of seats. The release, however, might remain in the unlocked position, allowing the seats to move unexpectedly. This condition increases the risk of injury to the seat occupant during a crash, NHTSA said.

To fix the problem, dealers will install an additional bracket and spring to both second-row outboard seats. There will be no charge for this service. Honda’s identification number for this recall is KD5.

The second recall covers 7,549 Odyssey minivans in the 2016 model year. In these vehicles, a horizontal adjuster bar for the second-row center seat may stick in the unlocked position. As a result, the seat might unexpectedly slide and pose a safety risk in the event of a crash, NHTSA said. Dealers will make an inspection and replace the horizontal position adjustment bar if needed. There will be no charge for this service as well. Honda’s identification number for this recall is KD4.

Both recalls are expected to get under way Jan. 23. Honda can be reached at (888) 234-2138.