A hydraulic leak required a full power-unit change.
McLaren now turn its attention to next week’s final pre-season test in Barcelona.
Jenson Button: "I still can’t comment on where the car will be when everything is running smoothly, as I haven’t had the chance to run it properly without meeting problems."
The in-season development is both a blessing and a curse for Formula One teams.
No fireworks from new engine so far, as team logs laps with brand new MP4-30 contender.
Some news that won't be received well by Honda.
F1 engine suppliers Ferrari and Renault appear to have won a battle in the long-running 'freeze' saga.
A press conference has been set for tomorrow morning.
They're back and now it's real: the much expected Honda Formula One engine may still be under development, but the manufacturer decided to use this weekend's Japanese GP to offer a sneak peak of its 2015 power unit.
McLaren's current car is a "rolling laboratory" for the start of the works Honda era beginning in 2015.