Servicing substance halted Nico Rosberg's F1 Mercedes in Singapore

Following the problems that forced the 2014 F1 title contender out of the Marina Bay race, Mercedes flew the faulty steering column parts back to its Brackley factory for detailed analysis this week.

That intense forensic investigation revealed that the steering column electronics were contaminated with an unspecified foreign substance that is used during pre-event servicing procedures.

The presence of the substance went undetected throughout the Singapore GP weekend and there had been no hint of any problems prior to Rosberg sitting in the car shortly before the start of the race.

However, once the problem struck it produced an intermittent short circuit that meant Rosberg could not control the clutch or change engine settings.

The lack of controls - and specifically having no clutch for his pitstop - meant he had to retire from the race.

The circumstances surrounding Rosberg's failure are particularly mystifying because Mercedes has used the same steering column electronics design - and same pre-event servicing procedures - since 2008 without a single problem before.

Mercedes is taking no risks from now on, however, and has elected to use completely fresh parts for the final five races of the season.

Team boss Toto Wolff made it clear after the Singapore race that it was surprising Mercedes continued to suffer reliability problems despite ramping up its efforts in this area.

"We have a great reliability team," he said. "This is a group of people who are really dedicated to reliability and I am really proud of them.

"So it is even more astonishing we keep having those issues. They need to get a grip, but this takes time."