Aston Martin technical director Dan Fallows has left his role with the Formula 1 team.
The 50-year-old, who joined the team in 2022, will "remain with the group", Aston Martin said.
Executive director Bob Bell, a highly regarded and experienced design engineer who joined the team in March, will fill in on a temporary basis.
Fallows' departure is a move driven by new chief executive officer Andy Cowell. The former head of Mercedes' F1 engine programme started at Aston Martin in October.
It follows a slump in performance from Aston Martin after a promising start to the 2023 season, when lead driver Fernando Alonso scored six podiums in the first eight races.
Aston Martin fell back in the second half of last season as the team failed to develop the car successfully.
The same pattern has emerged this year, which the team did not start as competitively. Alonso's highest finish in 2024 is fifth, and the team are fifth in the constructors' championship.
Fallows, who joined from Red Bull on a salary in the region of £1m, said in a statement: "It has been a joy and a privilege to guide the technical team on their journey towards being race and championship winners.
" It is time for me to pass on the baton, but I look forward to watching the team's future success, which I am sure will come soon."
Aston Martin owner Lawrence Stroll has the ambition for the team to become championship contenders and has recruited Adrian Newey from Red Bull to lead their F1 design.
Newey starts work in March next year on a salary that could reach £30m, which is reflective of a career in which he has won 13 drivers' championships and 12 constructors' titles with Williams, McLaren and Red Bull.
Aston Martin have also signed former Ferrari chassis technical director Enrico Cardile as chief technical officer, but the two teams are still negotiating his start date.
The plan is to appoint a new technical director, but likely only after Newey and Cardile have started work and decided their plans.