Toyota's Ralf Schumacher was ordered to add a half second penalty to his Monaco Grand Prix aggregate qualifying time after a tyre error in free practice on Thursday.
Stewards summoned the German, younger brother of Ferrari's seven-times world champion Michael, and a representative of the team after Ralf was found to have used a left front tyre that had not been officially allocated to him.
Supplier Michelin blamed human error. Qualifying is on Saturday and Sunday.
The time penalty will be Ralf's second in three races. He lost a point at the San Marino Grand Prix after being given a 25-second penalty for a pit lane offence.
Ralf was ninth fastest in free practice on Thursday.