Toto Wolff has described the repeat of Lewis Hamilton's MGU-H problem at the Russian Grand Prix as "a freak failure".
Hamilton was hit by ERS trouble in China, with Mercedes pinpointing the problem to the MGU-H as the triple world champion started from the back of the grid. At the end of Q2 in Russia, Hamilton suffered the same problem and Wolff says it comes as even more of a surprise after the first one was rectified.
"I would say that what happened today is a bit of a freak failure because it is a scientific assessment process and we had a failure in Shanghai that we understood," Wolff said. "We decided to change the parts and here we go again, the same thing happens so we need to find out if we have identified the root cause of the problem.
"The car is rock solid, it is a fast car, this weekend probably the fastest so far as we have had these two unfortunate problems on the MGU-H."
Wolff wants Mercedes to look at the way it is running Hamilton's car in case settings are to blame for the problem, but ruled out the driver as having any influence.
"I think we have eight power units out there and seven didn’t have any problems and one had a problem twice.
"You need to turn every stone and looking at settings, because it happens in the same circumstances in qualifying twice or in the race, so I wouldn’t exclude anything but it is not something that is obvious because we would have found out.
"It isn’t the driver’s fault, that is definite."
REPORT: Rosberg takes pole as ERS problem hits Hamilton
AS IT HAPPENED: Russian Grand Prix - Qualifying
Romain Grosjean column: Haas brought back down to earth
Keep up to date with all the F1 news via Facebook and Twitter
When F1’s radically redesigned 2026 cars finally roll out in Barcelona at the end of…
Max Verstappen has never been one to sugar-coat reality – and as Formula 1 braces…
Ferrari have survived decades of criticism about strategy calls, driver politics and pit stops that…
While the paddock has been whispering for months that Mercedes might be holding the winning…
Dan Gurney passed away on this day in 2018, and here at F1i we'll never…
What began as a painful reminder of loss has ended with a moment of profound…