This news is a huge blow to McLaren, as Lando Norris suffered a major setback in his bid to close the gap on his title rival Max Verstappen.
It all began when Norris was handed a five-second penalty, following his impressive drive in the United States Grand Prix.
The British driver was left grinding his teeth after being given the penalty, which pushed him down the leaderboard and dealt a massive blow to his championship hopes.
McLaren lodged an appeal, citing several key factors, but their bid to overturn the penalty has been rejected.
The original decision has been upheld, leaving Norris with a difficult task as he looks to claw back into the title fight.
His penalty also gave Verstappen a welcome reprieve, and the reigning champion now looks well-placed to extend his championship lead.
McLaren remains optimistic that Norris can turn his season around and produce some late fireworks to rekindle their championship hopes.
However, their chances look bleak at the moment, and Norris' penalty in the US Grand Prix may ultimately prove to be a crucial turning point in the season.