Helio Castroneves says he was "very shocked" to learn his race-winning car at Texas had failed post-race inspection.
IndyCar fined Penske Racing $35,000 and docked Roger Penske 15 owner points this week because the underwing height on Castroneves' car was too low.
Penske officials said the problem was because the team failed to tighten braces on the car, and the team sent the car to the wind tunnel on Monday to see if the part gave Castroneves an advantage. The team said Castroneves was actually at a disadvantage because of the error.
Castroneves said Friday at Milwaukee it was important for the team to prove his car did not have an illegal performance advantage.
But he also says he will not allow the penalty to overshadow last week's run.