Red Bull had to turn down Max Verstappen's Honda engine during the Bahrain Grand Prix, according to Helmut Marko.
The Dutch driver almost clinched victory from Mercedes' Lewis Hamilton, having hunted down the leader after being undercut at the first round of pitstops.
Marko has revealed that Verstappen's engine was not able to run in a higher power mode during the race, due to temperature concerns.
"The problems we had were primarily software related. Nothing in the hardware, so things that you can fix with adjustments," Marko explained to Formel1.de.
While the use of engine modes for performance purposes are no longer permitted, teams are allowed move their engines into lower power settings for the sake of reliability, like in this case. Even if the issue later clears up, teams cannot return to the original power setting.
This issue was added to a differential issue that caused some rear wheel slipping for Verstappen during the race, which he complained about over team radio throughout.
"At the beginning of the race he had problems in the differential area and last sector more specifically, even drastically, up to three tenths per lap," Marko explained.
"But still, Max drove accordingly."
Despit the issues, Verstappen finished just 0.7 seconds away from Hamilton after closing back up following his final pitstop and an unsuccessful overtaking attempt.