Honda brought a turbo and MGU-H unit updated to the Bahrain Grand Prix after Gasly's engine problem at the Australian GP, and both pilots will have their second unit.
While the Toro Rosso-Honda partnership worked fairly well in pre-season testing, there were no problems with the motors during the test. However, the engine problems arose in the first round of the Australian Grand Prix and Gasly had to leave the race.
Toyoharu Tanabe, the Technical Director of Honda's F1 Project, explained that Gasly's power unit was damaged in turbo and MGU-H parts.
Honda changed its turbo and MGU-H units in order to avoid the same problem again before the race to be held this weekend.
The parts of Hartley's power unit were also replaced as a precautionary measure, as both units on Gasly's vehicle were changed forcibly.
However, since the problem that Gasly suffered in Australia has also damaged the internal combustion engine, the French driver will still have to switch to a second one after the first race.
This year Formula 1 pilots can use three internal combustion engines, MGU-H, and turbo. Apart from that, they get a grid penalty for any changes made.
If Honda can not get the previous parts to work, there will be only one internal combustion engine, turbo and MGU-H units that Gasly can use without penalty of 20 points throughout the season.
The same applies to the second MGU-H and turbocharged Hartley, but the only difference from the teammate is that the internal combustion engine is in operation.
Tanabe said, "It is certainly a difficult decision and certainly not perfect given the fact that parts of the power unit in the second race will be limited to three pieces of parts that can be used this year."
"But we think this is the right way and we are trying to keep on developing so that the same problem does not happen again." said.
Both pilots will continue with the same energy storage, control electronics and MGU-K.