Williams chief technical officer Paddy Lowe is to take a "leave of absence" from Formula 1, the team confirmed to reporters on Wednesday.
The team missed the opening two and a half days of testing for the 2019 season due to the late completion of the car, with deputy team principal Claire Williams describing the delay as "embarrassing".
Williams' 2018 car finished bottom of the championship -- the team's worst ever season -- although both Lowe and Claire Williams insisted throughout pre-season that his job was safe.
But a spokesperson for the team said that Rowe will be "taking a leave of absence from the business for personal reasons", in a message sent to a media WhatsApp group.