The PU change will mean the Spaniard, who finished third last time out, will start from the back of the grid at Istanbul Park.
The move was expected after Leclerc was given the first unit update, with Sainz’s change delayed to space the penalties out and ensure there were not two Ferraris at the back of the grid.
“As was the case for Charles Leclerc in Russia, in Turkey Carlos Sainz will take a completely new power unit fitted with the new hybrid system,” a Ferrari statement said.
“Therefore, he will start from the back of the grid with the aim of climbing up the order to try and score some points.”
The new hybrid system is effectively being race tested with a view to 2022, with Leclerc stating in Russia the Scuderia should not expect big leaps in performance from this sole upgrade.
The Monegasque explained: “We expect it to be a little bit better. We don’t expect any big, big changes but something that goes in the right direction.”