While Lewis Hamilton won at Monza recently, Jenson Button would probably have finished second if not for a fuel system problem.
With the former world champion's title hopes seriously dented, the British team returned from Italy unsure what caused the failure.
"It was a problem that we haven't had before and it wasn't an easy one for us to identify," technical director Paddy Lowe said in the regular Vodafone teleconference on Wednesday.
"We have fortunately managed to identify the root cause and it was a problem with the fuel pump. It's something we have now completely covered for the remaining races."