Red Bull Racing has announced that it concerns a problem with the ERS, or the Energy Recovery System.
Helmut Marko confirmed this to Motorsport.com in the paddock, but said that the exact cause has yet to be found.
"It's a problem with the engine. We now have to take the engine out of the car to find the exact cause, but it is certainly
on the electrical side of the engine."
Judging from the FIA documents, Verstappen has also added a new power source to his so-called pool today, but Marko emphasizes that the new one is not broken.
"No, this is not a new engine, but an old one."
https://nl.motorsport.com/f1/news/f1-up ... /10620828/
Edit:
??? Horner: "We’ll have a lot of work to do tomorrow in FP3 to get an understanding on where we can get the car before qualifying.
It looks like an ERS fault on Max’s car, something we’ll continue to investigate and resolve into the evening
to be ready for tomorrow."
So it was the new PU??