Honda is confident its solid day of testing in Bahrain last week offered the direction it needs to overcome its latest reliability issues.

McLaren-Honda suffered a spate of MGU-H failures over the Bahrain Grand Prix weekend and on the first day of the following week’s in-season a water leak on the Energy Recovery System kept the car in the garage for the majority of the day. The problems were traced to the MGU-H, which is the part of the power unit that harvests energy from the engine’s exhaust gasses via the turbo and can also be used to control the speed of the compressor.

Following a full power unit change during the test, Stoffel Vandoorne was able to run reliably for 81 laps on the second day using the same spec of MGU-H as before — allowing the team to turn up some of the car’s performance settings and complete its entire run plan.

“After a disappointing grand prix weekend in Bahrain, we have since had an extremely busy few days during in-season testing, also at the Bahrain International Circuit,” Honda F1 boss Yusuke Hasegawa said. “The team has been working hard to implement some countermeasures to help combat our MGU-H issues.

“By the second day of testing, we think we were able to confirm the direction of our solution against the issue after completing 81 laps with Stoffel behind the wheel. The results are testament to the team’s hard work and determination.”

This weekend’s Russian Grand Prix will be the first opportunity for Honda to put its solutions to the test, but despite a double points finish at last year’s race, Hasegawa admits Sochi’s straights will still present the team with a few issues.

“The 2016 Russian Grand Prix saw McLaren-Honda finish the race with two cars in the points, so of course we will do our best to try and replicate this. That said, I expect the Russian Grand Prix will be another challenging race weekend for us.

“The nature of the track, with its long straights combined with 90-degree corners, means the race will be stop-start, putting emphasis on the balance of energy management. Unlocking power and managing fuel will also be key. We will of course work hard with McLaren during the practice sessions in order to find the best set-up, and we are hoping to show a good performance.”