Alex Albon has been disqualified from Saturday's qualifying session for the Dutch Grand Prix after the dimensions of his car's floor were deemed to be outside the regulations.
The Williams driver qualified eighth -- his best result of the season -- but a post-session check by the FIA's technical delegate found the volume of the car's floor was outside the regulations.
The floor of the car has the potential to generate a significant amount of downforce, and the volume of the tunnels under the car is strictly controlled by the regulations.
Williams introduced a new floor and diffuser as part of a raft of upgrades to the car at the Dutch Grand Prix.
The FIA's technical delegate referred the issue to the stewards at the Dutch Grand Prix, who determined Albon should be disqualified.
In a statement, Williams said it was "incredibly disappointed with this outcome" and would carry out a "thorough investigation."
The stewards statement said the FIA's measurements had produced a different result to the team's.
"The floor body of Car 23 was found to lie outside the regulatory volume mentioned in Article 3.5.1 a) of the FIA Formula One Technical Regulations," the stewards' statement said.
"The team did not dispute the calibration of the FIA measuring system and the measurement of the car, but stated that their own measurements have produced different results.
"The stewards determine that the result of the measurement conducted with the FIA system in Parc Ferme is the relevant one and the due process prescribed by the regulations has been followed. Therefore the standard penalty for such an infringement is applied."
Albon's Williams teammate, Logan Sargeant, did not participate in qualifying at Zandvoort after crashing heavily in final practice.