The American badly damaged his car during a high-speed crash in qualifying on Saturday, which has forced a change of chassis.
The FIA discovered, however, that the team had assembled its spare car far more than was normally allowed according to the rules – so it was in effect judged to be a third car.
Williams was summoned to the stewards on Sunday morning and explained that the problem was triggered by its mechanics beginning work on making up its spare chassis as soon as it became clear it had to be done. This was in theory done before teams are allowed to start such work.
Following the stewards’ hearing, the FIA accepted the explanation from Williams about what happened, but said that it was mandated for it to hand down a penalty.
With the change of chassis already automatically meaning Sargeant must start from the pitlane, it was decided that a further 10-second penalty would be given.
A statement from the FIA said that it was aware of there being an issue in the rules whereby a team risked not being able to make the start of the race if mechanics did not begin work until after parc ferme had ended.
It said: “It should be noted that the available working time during Parc Fermé for assembly of a complete car is limited, and hence in case of severe accident like this, the Stewards may jeopardise the participation of a car in the race.”
The timing of when mechanics should be allowed to begin work on the car is something that is now up for discussion in F1’s Sporting Advisory Committee.
Williams head of vehicle performance Dave Robson said that parc ferme limits had meant the squad had needed to get a move on to ensure Sargeant could start the race.
“Obviously, we're not allowed to do very much overnight,” said Robson. “So it's been sat there with the covers on.
“We got the spare chassis out and did as much as we could for that. The team is just getting on with a build now. It'll be tight, but it'll be fine. No problem.”
Asked what Williams had to replace on the car, Robson said: “Almost everything. It will have spare chassis, spare power unit. A previously used one, so no additional penalty. Spare gearbox. Same thing, a previously used one. Floor, rear wing, front wing.”
