Nov.6 (GMM/Inautonews.com) Christian Horner has admitted “human error” led to Sebastian Vettel having to start Sunday’s Abu Dhabi grand prix from the back of the field.

After qualifying third in Abu Dhabi, the championship leader was asked by his Red Bull engineer to “stop the car” on the track, apparently with a technical problem.

But when the scrutineers tried to extract the mandatory 1-litre fuel sample from the RB8, the pot fell a few hundred millilitres short, resulting in the German’s disqualification.

He started the race from the pitlane, Vettel only rescuing his title lead by charging through the field to third.

So what happened at the end of qualifying?

“To be honest, we have no clear answer but I suspect that it was human error,” team boss Horner is quoted by Germany’s Sport1.

“Renault gave us a clear statement that we should stop the car. Because we feared that it could be something that damages the engine, we followed their instructions,” he added.

“We had to explain to the stewards why we stopped the car, they accepted our argument, but then we had to give the one litre sample.”

Horner said Renault has not been able to explain why too little fuel was put into the RB8.