Reliability issues that followed Lewis Hamilton and Jenson Button as McLaren teammates last season made an appearance in preseason testing in southern Spain on Tuesday.
As Button completed his third lap around the Jerez circuit, the redesigned MP4-28 sputtered to a halt 10 minutes into testing with suspected fuel delivery problems.
The 2009 world champion helped team workers cover the car before a truck arrived to transport it back to the pits. By early afternoon he'd yet to complete a competitive lap.
Nico Rosberg, Hamilton's teammate at his new outfit Mercedes, suffered a more spectacular car failure as a flash of flames followed by smoke erupted from the rear of his Silver Arrow, having just set a lap time of 1 minute, 20.3 seconds.