Lewis Hamilton looks set to keep his pole position in Spain, despite stopping on the track whilst returning from parc ferme at the end of qualifying.
The McLaren driver was told on the radio to park the car immediately due to a problem, but his engineer would not immediately explain the nature of the issue.
"I was told to stop. I have no idea why," the 2008 world champion told reporters in Barcelona.
Team boss Martin Whitmarsh told British television Sky that the problem is not engine or gearbox related, meaning that grid penalties will presumably not apply.
Whitmarsh however acknowledged that McLaren is yet to fully "understand" the problem. "It’s a little bit of a worry," he admitted.