Daniel Ricciardo was unable to use seventh and eighth gear after encountering the engine issue which nearly robbed him of another Monaco Grand Prix win.
Ricciardo led the race from the opening lap having claimed a dominant pole position on Saturday and looked to have it under control until he reported a loss of power on lap 18. The Australian had suffered a loss of full power from his Renault engine, causing him to be 20 km/h slower down the straights.
Reflecting on the moment he had lost power, Ricciardo, who lost a Monte Carlo victory because of a botched pit-stop in 2016, said he was sure another one was slipping from his grasp.
"The start went well and I was like I've pretty much done the hard part let's just finish this race and then I think lap 18 or something I exited one corner and I just felt pretty much no power compared to what I am used to. I wanted to close my eyes and start crying because I thought that was it, that my race was over,'' Ricciardo told Sky Sports.
"We changed a lot of things, it didn't fix the problem but we had to just survive with our problem all race so that wasn't fun. It sucked. I am exhausted and I look forward to a drink very soon.''
Not only was the faulty MGU-K costing Ricciardo time on the straights, the issue caused his rear brakes to significantly overheat.
"I only used six gears for the rest of the race. We got eight in a Formula One car so that's kind of an example of how down on power we were. We don't all use eighth here, it's a short track but we were still down a lot. I was just managing the tyres a lot.
"At the end I was pushing a bit more but it was still costing me, I don't know, I would say over a second, definitely over a second a lap, it was a lot and also because that the rear brakes get hot, because of the 'K' that failed, so the rear brakes got really hot we had to go seven percent forwards with the brakes.
"For example, maybe we change it one or two percent during a whole race so to go seven percent is a lot. A lot of things to manage but we did it. And who cares. We did it.''