Inspectors confiscated the fuel cell from Truck Series points leader Johnny Sauter this weekend at Kansas Speedway and will review it the first part of next week.
NASCAR did not say what issue was found with the fuel cell, which was taken Thursday during the opening day inspection. Any potential penalties would also be handed down next week.
Sauter won the first two races of the season at Daytona and Martinsville, and finished fourth at Rockingham. He stayed out of trouble in a crash-filled race Saturday at Kansas to finish fifth, maintaining a 12-point lead over Matt Crafton in the series standings.
Crafton held off Joey Coulter over the final 20 laps to win Saturday's race.