Honda thinks Vandoorne suffered repeat of Monza qualifying issue

Vandoorne spent much of the race in the top 10, running as high as seventh, but reported a loss of power and was recalled to the pits to retire the car.

Honda boss Yusuke Hasegawa said the supplier was still investigating the problem, but believes it could be same issue as occurred during the final part of qualifying.

Vandoorne was set to start in the top 10, but Honda identified a problem with the MGU-K shaft and as there was not enough time to change it before the start of the race, it elected to fit a new engine.

"We still haven't broken down the engine, but definitely the MGU-K was not working," he said. "It could be the same issue that we have on Saturday. The driveshaft wasn't completely broken."

Honda says it does not know why the the MGU-K shaft broke on Saturday, particularly as it was a low mileage part.

"This is very low mileage, so we applied new shaft on Saturday morning. It had 200km. On Sunday, it was almost the same mileage. It might be a manufacturing issue or batch issue. Normally it lasts more than 800km."

Hasegawa conceded Honda has been changing the part frequently this season to control the mileage.

"We had a mileage issue, that's why we are managing mileage," he said. "So every event we are changing so we are confident about mileage control."

Hasegawa added that it will be possible to replace the MGU-K shaft without incurring a penalty for the upcoming Singapore Grand Prix.

The broken parts will be sent back to Sakura for investigation, with Honda hopeful of finding the root cause of the problem.