McLaren are to modify the rear wing they used to win the Azerbaijan Grand Prix after rivals raised questions about its legality.
Governing body the FIA said the wing, which was seen on television footage flexing at high speed, had passed all deformation tests. It initially did not intend to require any changes from McLaren.
However, the FIA changed its stance after complaints by rivals, primarily Red Bull, and conversations with McLaren.
McLaren can continue to use the wing but must change it so that it does not behave in the same manner as was seen on television footage in Baku.
A rearward facing camera on the car of race-winner Oscar Piastri showed that the edges of the wing flap flexed upwards at high speed down the long straight in Baku.
Red Bull have not made a public comment about the wing but team principal Christian Horner is said by sources close to the matter to have been lobbying hard behind the scenes for the FIA to take action.
Ferrari team principal Frederic Vasseur said: “The front wing we all agree that it could be a grey area. The rear wing is different because (defined) in the article (in the regulations) there is a maximum deflection and this is black or white, no grey.”
Vasseur said the wing was “more than borderline” and that the matter was “frustrating” in the context of the close competition at the last two races at Monza and Baku, at both of which the wing was used.
Ferrari’s Charles Leclerc won the Italian Grand Prix after McLaren secured a front-row lock-out. Piastri finished second in Monza with team-mate Lando Norris third.
In Azerbaijan, Leclerc was passed for the lead by Piastri at the end of the pit straight and the Australian went on to secure the second victory of his career.
The ruling affects only the rear wing McLaren will use at high-speed, low-drag circuits so will not affect the team at this weekend’s race in Singapore, or the subsequent races in the USA, Mexico or Brazil.
And there will be no retroactive punishment for McLaren on the matter.
The next race at which the wing was likely to have been used is the Las Vegas Grand Prix in November.