"Forensic analysis has revealed that the steering column electronic circuits were contaminated with a foreign substance," the team tweeted on Friday afternoon. "The contamination was not visible and did not manifest itself until Sunday as Nico went to the grid. The result was an intermittent short circuit in the electronic circuits meaning Nico could not command clutch or engine settings.
"Fresh parts will be used at the forthcoming races," the team added. "Our hard work on reliability processes will continue at the same intensive level."
Rosberg's retirement meant that teammate and title rival Lewis Hamilton, who won the race, was able to leapfrog the German in the championship, turning what was a 22 point deficit into a 3 point lead.
Speaking earlier this week, team boss Toto Wolff admitted that the German team must get on top of its reliability issues.
"If we could do anything more to prevent further retirements we would be doing it," said Wolff. "I would break my arm again to make it happen!. It's something we need to get on top of – we have a missile of a car but, in terms of reliability, we are having issues.
"We have a great group of people in our reliability team who are dedicated to quality," he added. "We're very proud of the structures they are putting into place – and that's what makes it even more astonishing that we keep having these issues. These things take time to get a grip on – but we will not stop until we stop suffering these DNFs. We have had four of them now and it would not be satisfying at all to have the Championship decided because one car let the driver down. We need to refocus, get our heads down and keep concentrating on preventing these reliability problems reoccurring."