F1 teams are forbidden from making changes to their car’s set-up, apart from to the front wing angle, from the start of qualifying, under what are known as parc ferme regulations.
The part in question that could be adjusted was the so-called ‘bib’ or ‘tea-tray’, which is the front of the floor in the middle of the car.
An FIA statement said: “Any adjustment to the front bib clearance during parc ferme conditions is strictly prohibited by the regulations.
“While we have not received any indication of any team employing such a system, the FIA remains vigilant in our ongoing efforts to enhance the policing of the sport.
“As part of this, we have implemented procedural adjustments to ensure that front bib clearance cannot be easily modified.
“In some cases, this may involve the application of a seal to provide further assurance of compliance.”
Sources close to the situation say the FIA was informed of the device on the Red Bull over the course of the Singapore Grand Prix weekend last month.
Rivals had seen its existence in what are known as open-source component documents that teams have to provide to the FIA about the design of their cars.
The ability to adjust the floor of the car would enable teams to better balance the demands of qualifying and racing.
A team would prefer the car to run lower in qualifying and higher in the race.
The F1 season resumes this weekend after a four-week break with the United States Grand Prix at Austin’s Circuit of the Americas.
Red Bull’s Max Verstappen leads the drivers’ championship as he pursues a fourth consecutive title.