Stoffel Vandoorne faced fresh mechanical trouble in his McLaren-Honda on the second and final day of the Paul Ricard wet weather test on Tuesday.
Having been forced to stop early on Monday following a warning about his 2015 Honda engine, which was a high mileage unit, the Belgian had to drop out of a stint early on Tuesday morning to return to the pits.
McLaren and Honda engineers were seen working on the rear of the car while other teams continued their running, before he was able to rejoin the track action.
High mileage parts
Under the FIA rules of the test, teams and their engine partners are only allowed to use 2015 components, which means that parts being used are at the end of their life.
For McLaren and Honda, it should mean at least that the Vandoorne issues are just a legacy of its difficult campaign last year rather than a precursor to fresh trouble for its revamped 2016 effort.
After Kimi Raikkonen tested for Ferrari on Monday, Sebastian Vettel took over duties on Tuesday , fresh from his run in a 2014 car at Fiorano last week.
The German quickly moved himself to the top of the time sheets, as drivers conducted longer stints than Monday for Pirelli to evaluate more prototype designs.
Daniil Kvyat replaced Daniel Ricciardo at Red Bull.
Additional reporting by Benjamin Vinel