Busch failed postrace tech inspection Saturday after finishing ahead of Austin Cindric, who was declared the winner for the third victory in a row after winning both Xfinity races at Kentucky.
NASCAR said the No. 54 Joe Gibbs Racing Toyota was disqualified for failing heights.
It would have been the 98th career win for Busch in the series. Instead, Cindric got his fifth in 83 career starts despite crossing the finish line 0.949 seconds behind Busch.
After coming back through the field three times in the race, including an early speeding penalty on pit road, Busch built a 3.3 second-lead before a final caution flag when Joe Graf Jr. made contact with the wall. Busch led only 15 of the 201 laps.
Justin Allgaier regained the lead from Cindric when both pitted on lap 159, but was penalized for a blend line penalty when getting back on the track. After doing his pass-through penalty 10 laps later, he dropped two laps off the pace. and wound up finishing third, behind series points leader Chase Briscoe.
“I’d like an explanation, because that’s been the same way we’ve done it now for as long as I’ve been in NASCAR,” Allgaier said. “Disappointing. ... Win the two stages and know that we had a car that was capable of going for a win was really a solid afternoon.”
Cindric led three times for 44 laps. Allgaier, who won both stages during the race, was in front four times for 98 laps.
There were no spectators allowed for the Xfinity race, or the Truck Series race on Saturday night when Busch was racing again. Thousands of fans will be in the stands for the Cup race Sunday.
Noah Gragson, who entered the race second in season points, crashed in Turn 3 on lap 117 after he got loose after the air got taken off his rear with Cindric behind him. There didn’t appear to be any contact. Gragson finished 31st, and dropped to third in points while Cindric moved up to second.
Gragson was behind Riley Herbst in a similar incident on five laps into race, when Herbst slammed hard into the outside wall coming out of Turn 4 and ended his day to finish last in the 37-car field. Gragson said on the radio that there was no contact.
“We were just learning the track here at Texas, first time at this speedway and got absolutely drove through by the 9 (Gragson) car,” Herbst said. “Just a little bit of lack of respect.”