Red Bull Racing has been asked by the race stewards at the Abu Dhabi Grand Prix to explain why Sebastian Vettel's car did not return to the pits after his qualifying lap.
The German bounced back from a troubled final practice session to secure third place on the grid - behind Lewis Hamilton and Mark Webber.
However, towards the end of his in-lap, Vettel was ordered over the radio to stop his car immediately and he pulled over at Turn 19.
Formula 1 regulations state that drivers must return to the pits after qualifying under their own power so that a one-litre fuel sample can be taken from the car for analysis.
Article 6.6.2 of the technical regulations states: "Competitors must ensure that a one litre sample of fuel may be taken from the car at any time during the event.
"Except in cases of force majeure (accepted as such by the stewards of the meeting), if a sample of fuel is required after a practice session the car concerned must have first been driven back to the pits under its own power."
Both Red Bull and engine supplier Renault were silent on Saturday about the exact reasons for Vettel stopping, but the stewards demanded that representatives from both companies explain what happened.
At the Spanish GP earlier this year, Lewis Hamilton was stripped of his pole position and thrown to the back of the grid after he was told to stop on the in-lap to ensure that he had enough fuel on board for the sample.