McLaren's troubled pre-season campaign has suffered another setback after they encountered further engine problems on the opening morning of the concluding winter test.
The British team were keen to bounce back from a disappointing week in Barcelona in which a number of reliability issues with their Honda engine plagued their running.
An electrical fault however, restricted Belgian driver Stoffel Vandoorne to only 34 laps of the Circuit de Catalunya.
McLaren will replace the engine and intend to get back out on track later this afternoon.
But the latest issue will come as a significant blow, both to the British team and their beleaguered engine supplier Honda, with just three full days of testing remaining before the season gets under way in Melbourne on March 26.
McLaren are looking to overturn a miserable run of form which has seen them fall down the grid in recent seasons. They have not won a race since Jenson Button triumphed at the 2012 Brazilian Grand Prix.
But their new car has been hampered by engine issues and only Toro Rosso completed fewer laps than McLaren at the opening four-day test in Barcelona last week.
Double world champion Fernando Alonso, who will return to the McLaren cockpit on Wednesday, is entering the final year of his contract with the British team, and has been non-committal on his future beyond this season.
Aside from McLaren's woes, Williams driver Felipe Massa posted the fastest time in the morning session with Red Bull's Daniel Ricciardo second in the order and Lewis Hamilton third for Mercedes.
Ferrari's Sebastian Vettel completed more laps than any other driver. Britain's Jolyon Palmer managed only 15 laps for Renault and was the slowest of all 10 runners.
Meanwhile, Germany's Pascal Wehrlein returned to action for Sauber after missing the opening test with the back injury he sustained at the Race of Champions exhibition event in Miami in January.