Ferrari doubts there was a discrepancy between the amount of fuel found in Charles Leclerc's car for Formula 1's Abu Dhabi Grand Prix and its pre-race declaration, Autosport understands.
Ferrari was fined €50,000 in Abu Dhabi after FIA checks found there was 4.88kg more fuel in the car than had been declared by the team.
It has now checked its figures again since the infringement, and Ferrari cannot explain why the FIA's fuel weight figure is different from its calculation of what was in the car.
The procedure regarding the amount of fuel in the car is covered under a technical directive - TD12-19 - which was issued before the start of the season.
Teams have to declare the amount of fuel they intend to put in the car - which covers the laps to the grid, the formation lap, the race and the in-lap - at least two hours before the pitlane opens.
The FIA can then conduct random checks before the pitlane opens to check the declaration matches the amount of fuel in the tank.
It was during one of these checks on Leclerc's Ferrari that the FIA discovered a difference between what Ferrari had declared and the amount of fuel it believed was in the car.
But it was not until 16.22 - eight minutes before the pitlane opened for the start of the race - that Ferrari was notified the FIA had found this discrepancy.
By that stage, it was too late to request a second check on the amount of fuel and, once Leclerc had left the garage, there was no way of proving the fuel amount.
As a result of the FIA finding the discrepancy, Ferrari was summoned to a post-race hearing, and the team was given a €50,000 fine for a breach of the International Sporting Code.
The FIA ruled that Ferrari broke Article 12.1.1.i of the ISC, which states that there was a "failure to follow the instructions of the relevant officials for the safe and orderly conduct of the Event".
The stewards said there was no technical rules breach, meaning there is no suggestion that Ferrari may have burned more than the 110kg allowed for the duration of the race.
Ferrari is understood to be unsure why there was a discrepancy because its calculations of the fuel in Leclerc's car remain in line with the declaration it made before the race.
It does not believe it made an error with its declaration, and Ferrari remains convinced that the amount of fuel in the car matches that figure.
It is understood that a post-race check of the fuel remaining in the Ferrari, and how much had been used in the race, tallied with Ferrari's original declaration.
Ferrari is experienced in the fuel check procedures, and team principal Mattia Binotto claimed it has been a regular occurrence in 2019.
"It is not the first time we are doing it [having the fuel checked]," said Binotto. "This season we have been checked at least 10 times.
"It's not the first time and it has always been OK, and today we've got a discrepancy on which we don't know the [reason]."
According to FIA documents, several other fuel checks were carried out on all cars afterwards.
These covered fuel meter calibration checksums, instantaneous fuel mass flow, fuel temperature and total fuel mass consumed by all cars.
The FIA confirmed that all cars conformed to the regulations. Ferrari's doubt regarding the discrepancy means there can only be two options to explain the incident.
Either Ferrari somehow put more fuel in the car than it believes, something it is adamant it did not do and has found no evidence for, or the FIA's measurements during its checks were incorrect.
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