The 19-year-old has also signed a new contract at Manchester United, lasting until June 2024 with the option of an additional year’s extension.
Fernandez, who joined the club from Real Madrid in 2020, embarks on his first temporary move away from United.
He will be hoping to impress and receive regular game-time with the Lilywhites, who begin their Championship campaign away to Wigan Athletic on Saturday.
The move sees Fernandez join up with Ryan Lowe’s squad, which already includes three former Reds in Matthew Olosunde, Robbie Brady and Josh Harrop, as well as Benjamin Whiteman, who was with United up to Under-16s level.