After Red Bull's Sebastian Vettel and Lotus' Romain Grosjean both retired mid-race during the European Grand Prix at Valencia a fortnight ago with alternator problems, Renault have been busy looking into the problem.

While they believe they know the basic cause of the alternator failure, Renault engineers can't be sure that they've so far been able to fix it or totally ensure that there will be no recurrence in future races.

"The failure was due to overheating - overheating from within the piece, not from outside the piece," explained Renault Sport's Rob White at Silverstone on Friday. "Both Sebastian's car and Romain's car stopped on the track following the alternator failure. Clearly the alternator generates all the electricity on the car. Without electric power the car stops very quickly."

White explained that engineers had checked external issues such as whether the teams had been running the engine in a non-recommended manner, but had found nothing significant.

"We wanted to find out whether there was anything unusual relative to our recommended operating conditions. The truth of the matter is that both of the teams were completely within the recommendations we had previously made," White conceded. "There wasn't any change underway that went pear-shaped. The spec was something that has been stable for quite a long time - some years - apart from little details in the piece that actually broke.

"We had to look deeper," he continued. "We had to challenge ourselves on whether the recommendations we made were the right ones. We were able to find places where, with hindsight, we were at risk."

While the team found some areas where the unit was at risk, there has been limited time to put in any changes ahead of this weekend's British Grand Prix.

"We found some conditions where we felt we might have pushed the piece beyond its comfort zone and that's where we've had to focus our attention for this week," said White. "A very small amount of time to react. Without any great surprise, we don't have a magic wand to wave that will make all the trouble go away, so we've had to deal with it in a fairly classic way."

That's included reducing the electrical loading on the unit, and to remove component parts with the same batch number as those that failed at Valencia.

"It would be unjust to say that I'm 100 per cent confident we have done enough," White conceded. "We've got what is obviously a short-term plan for this weekend and in parallel we've got a longer-term look to see if we can do a more robust job for the future."

White added his thanks to Renault Sport's partners, including parts suppliers and the F1 teams.

"We've had great support from Red Bull and Lotus who suffered the failures and from Williams and Caterham who didn't but have identical pieces on the car," he said. "Also from all the suppliers in the supply chain."

Lotus F1 team technical director James Allison seemed happy with Renault's response to the problem that emerged at Valencia.

"We just work with Renault Sport ... We all just muck in together and try to get it fixed," he said. "I think it's probably just that the alternator was very near to the limit of what it could do. There's always a scattering components and one fell just the wrong side of the line."

And Adrian Newey said that while he was happy to work with Renault to address the problem, there was little in practice for him or the Red Bull team so do at this point. "It's a component failure that we'll work together to get on top of," he said.