McLaren boss Zak Brown warned on Friday of "massive consequences" if champions Red Bull were found to have breached Formula 1 rules on adjusting car set-ups during closed 'parc ferme' conditions.
Red Bull, who are trailing McLaren in the constructors' standings, have confirmed the presence of a ride-height device in their cars but insist it could not be accessed once they were fully assembled.
The team have agreed to make changes after discussions with the governing FIA, with the device likely to have seal attached to it at upcoming races until it can be removed.
Brown said at the U.S. Grand Prix there were still questions to answer.
He suggested Red Bull's statement was carefully worded, with cars not always "fully assembled" in parc ferme conditions and particularly when issues of driver comfort needed to be addressed.
"What doesn't quite stack up is the comment that you can't modify it," he told Sky Sports television. "If it's not accessible post or during parc ferme, then why put a seal on it?
"I think it needs to be a very thorough investigation because if you touch your car from a performance standpoint after parc ferme or in parc ferme, that is a black and white material, substantial breach which comes with massive consequences."
Brown said it was up to the FIA to "come up with a solution that is transparent and is satisfactory to all the teams.
"I think I'm not alone in our concerns for what we have seen and heard."
Rivals have raised concern that such a device could allow the car's ride height to be adjusted between qualifying and the race, which would be illegal but produce a performance advantage.
Brown said Red Bull appeared to be the only F1 team "that has the ability to adjust the ride height from inside the cockpit" although he accepted drivers would physically be unable to do so.
"Our questions are a bit more around what has maybe historically happened in understanding if it's been used in an inappropriate manner," he said.
Red Bull have won the last two constructors' championship, including the most dominant season on record last year, and the last three drivers' titles with Max Verstappen.
Verstappen is leading McLaren's Lando Norris by 52 points in the current standings with six rounds remaining.