Carlos Sainz will start the Monaco Grand Prix from the pitlane after being hit with a post-qualifying penalty.
The Spanish driver was under investigation for having missed the weighbridge call during Q1.
Toro Rosso driver Sainz was summoned to see the stewards after qualifying, and was handed a severe penalty.
Sainz has qualified in eighth position.
"The driver failed to stop for weighing during Q1 when signalled to do so by the red traffic light, the car was not returned to the FIA garage and work was undertaken," said the stewards.
"In accordance with Article 26.1 (iv) of the FIA Formula1 Sporting regulations the driver is required to start from the pitlane."
Sainz said before the penalty was announced that he could not see the light.
"I cannot see the red light when I pit. I cannot see that light," he said.
"I saw it late, but then the next one I stopped in the weighbridge and it was fine, so I don't think there should be a big problem.
"We cannot see it. That's it."