Camping World Truck Series points leader Johnny Sauter has been docked 25 points and his crew chief Joe Shear was suspended four races for an unapproved fuel cell found on the No. 98 truck during inspection at Kansas Speedway.
The penalties, which were announced Wednesday by NASCAR, also include a $10,000 fine for Shear and probation until Dec. 31.
Sauter, who opened the season by winning the first two races at Daytona International Speedway and Martinsville Speedway, had held a 12-point lead over ThorSport Racing teammate Matt Crafton. The penalty, however, drops Sauter into a second-place tie with Jeb Burton, 13 points behind Crafton.
The infraction was found during opening inspection April 18. Sauter went on to finish Saturday's race, which Crafton won, in the fifth position.
In a statement, NASCAR said the fuel cell safety foam in Sauter's truck had been modified without approval.
The next Truck Series race is May 17 at Charlotte Motor Speedway.