In fact, they seized it three sets, namely the one used by Ferrari, the one used by their B-teams and the third used to compare with the systems of the other teams. The investigation is expected to take at least a few days before they are at The FIA has released the results.
FIA commissioners are expected to check in particular a pipe running between the flow sensor and the motor itself, as this part is supposed to be the main apple of the dispute and a potential advantage for Ferrari, as in this way the engine is supposed to get more fuel per unit time than the rules allow.

The head of the Ferrari team, Mattia binotto, has repeatedly stressed that they did not cheat and that lower final speed in Austin and Sao Paulo has nothing to do with possible concealment of evidence: “We haven’t changed anything. It is important to know that since the beginning of the season, we have not changed either the fuel supply system or the way our power unit operates, " he added binotto.
Interestingly, the FIA opted for such an intervention, even though there was no official protest. Let's remember Renault the steering wheels were seized only after an official protest by Racing Point.
