Renault have been disqualified from the Japanese Grand Prix for having an illegal driver-aid system on their car.
Officials found that Renault's brake-bias adjustment system contravened rules dictating that drivers must drive the car alone and unaided.
Renault drivers Daniel Ricciardo and Nico Hulkenberg have therefore been disqualified from sixth and 10th places at the race at Suzuka on 13 October.
Renault have until 16:00 BST on Thursday to decide whether to appeal.
The ruling hinged on the details of what officials described as "innovative solutions" to adjusting the brake bias - the balance of braking from front to rear - around a lap.
Governing body the FIA rejected a protest made on the night of the Japanese Grand Prix by the rival Racing Point team that the system could be described as a pre-set lap-distance dependent brake-bias adjustment system.
Brake bias is adjusted by F1 drivers using controls and switches on the steering wheel.
Officials said the braking adjustment system on the Renault complied with the technical regulations because it "exploited certain ambiguities" within them.
However, they ruled that it did constitute a driver aid as outlawed under the sporting regulations.
The ruling said: "The brake balance adjustment system in question acts as a driver aid by saving the driver from having to make a number of adjustments during a lap."
The ruling added: "The stewards note that there is a clear distinction between this system and one which provides actual feedback control, which would be a substitute for driver skills or reflexes."
But it concluded that it did nevertheless constitute a driver aid.
Details of the operation of the system were not included in the ruling because it contained Renault's intellectual property and should remain "confidential in nature because (the stewards) evaluate data worthy of protection".
The decision promotes Ferrari's Charles Leclerc from seventh to sixth but does not affect the result of the constructors' and drivers' championships, both of which were secured by Mercedes in Japan.
Mercedes remain constructors' champions and only their drivers Lewis Hamilton and Valtteri Bottas can now win the drivers' championship. Leclerc is third but cannot catch Hamilton.