The car driven by Antonio Fuoco to a second consecutive WEC pole position in Friday afternoon's Hyperpole session has lost all of its times from qualifying and will now start from the rear of the Hypercar field for Saturday's 6 Hour race.
The #5 Porsche Penske Motorsport 963 LMDh will now assume pole position after Matt Campbell pipped the sole Chip Ganassi-run Cadillac V-Series.R of Alex Lynn by 0.008s.
The stewards report said: "After having checked the Technical Delegate report, the stewards considered the minimum car weight did not comply with the relevant regulations.
"Consequently, the Stewards decided to impose the disqualification of car 50 of the qualifying and hyperpole sessions and the deletion of the lap times of these sessions."
A Ferrari statement said the car "was found to be around 1 kg under the minimum weight mandated by regulations" and attributed the discrepancy to a new component fitted to the rear end after damage was incurred in collision with another car during FP3.
Fuoco had logged a best time of 2m02.600s to put a margin of 0.507s between himself and closest challenger Campbell.
That effort was fractionally slower than the 2m02.462s Fuoco had managed in the first qualifying session which set the top 10 that progressed to Hyperpole.
His team-mate James Calado in the #51 entry admitted that he "screwed up" as he missed the cut by 0.021s to Lynn.
He is now elevated to tenth on the grid, with the #50 machine Fuoco shares with Miguel Molina and Nicklas Nielsen set to start 19th.
LMGT3 runner-up also disqualified
The #95 United Autosports McLaren 720S EVO has also lost its second place in the LMGT3 category for the same infringement.
Josh Caygill had been 0.337s shy of polesitter Sarah Bovy's Iron Dames Lamborghini Huracan in the delayed Hyperpole session that was red-flagged early on following Alexander Malykhin's crash at Raidillon.
Caygill, Nico Pino and Marino Sato will also have to start from the back of the 18-car grid, with the WRT BMW of Ahmad Al Harthy moving up to join Bovy on the front row.
Speaking to Autosport following the McLaren's best qualifying showing of its short stint in the WEC so far, Caygill had said the result "just gives everybody such a boost, me included".
"The car feels genuinely very good here," said Caygill, who will step out of the line-up for Le Mans as Hiroshi Hamaguchi replaces him.
"As drivers, and a team, we're just really settling into the car round-by-round and just unlocking the next little bit all the time."
