To finish first, the old saying goes, one must first finish.

Nowhere is that racing truism more evident these days than at Mercedes F1, where the failure of a wiring harness knocked Nico Rosberg out of Sunday's Singapore Grand Prix after the 13th lap. It was a crushing setback for the German, who had been leading the championship and now trails teammate Lewis Hamilton by three points with five races to go. More troubling, it was the fifth time a Mercedes driver has been saddled with a Did Not Finish (DNF) by mechanical issues, a reminder that a reliable car is just as important as an ace driver.

Nico's problems seemed to come out of nowhere, at least for those of us not privy to the inner communications of the Mercedes F1 team. The car performed well in practice and qualifying, but had significant issues on race day. The first indication that something might be amiss occurred before Nico's car first left the pit garage. The team had the car up on jacks and was running through gear changes with the wheels spinning, which is unusual to see just before a race. More issues popped up during a practice start when leaving the pit lane just a half-hour before the race began. Rosberg sat at the end of the pit lane for longer than usual, before laying down a big strip of rubber during a burnout, suggesting problems with the electronically controlled clutch. The team replaced the steering wheel and reset the computer systems (like with an everyday computer, a simple reset can work wonders), but no luck.

Sunday's snafu was eventually traced to a faulty wiring harness connecting the steering wheel to the in-car computer. In your car, that might mean the "check engine" light comes on and you have to turn down the radio with the knob on the dash instead of the button on the wheel. But it can be disastrous in an F1 car, because almost everything is controlled from the steering wheel. Rosberg was able to drive the car, but couldn't make changes to the engine, differential, clutch and other vital functions or even, for a time, communicate with his crew. The car was, in effect, unfit for racing.

With the clutch—activated using a paddle on the back of the steering wheel–inoperable, Rosberg failed to get away during the formation lap. That forced him to start the race from the pit lane, and only after the rest of the field had cleared the grid. Rosberg did the best he could without critical functions like the drag reduction system or hybrid power that would have allowed the wickedly fast Mercedes to cut through the field. "I was only able to change gear," Rosberg says. Even shifting, another function done with paddles behind the wheel, proved difficult. The transmission would jump two gears at a time, leaving Rosberg with just first, third, fifth, and seventh gears.

Rosberg limped along for 13 laps, averaging more than 150 mph and keeping pace with the back of the field. But when it came time for his first pit stop, it went from bad to worse. He crept into the pit, where his crew changed all four tires, replaced the steering wheel, and attempted to get him going again. But with no clutch function to speak of, the car simply would not move, and Rosberg eventually called it a day.

Consistent Part Failures

Success in F1 requires consummate skill, of course, but it also requires a reliable car that performs consistently. A wiring loom is not a part anyone thinks much about. It’s not prone to failure like a transmission or engine full of moving parts. But it’s just as important, because when it fails, the car can’t race. And it’s not something that can be fixed mid-race by remotely restarting the computer, having the driver change a setting, or replacing a part during a pit stop.

Mercedes has been bitten by a range of part failures this season, coming from the engine (two DNF), the brakes (one DNF and two hampered races), the gearbox (one DNF), and now the wiring loom. We don't have any additional information about what caused this latest issue or how it might be prevented, but Mercedes team boss Toto Wolff says his team wants the championship to be decided on the track, not by reliability problems. "That would obviously be something which would not be satisfying at all," says Wolff. "We need to refocus and get our heads down, keep concentrating and find out what we can do."

When it's working, the Mercedes W05 is wickedly fast. In seven of the nine race in which both Rosberg and Hamilton finished, they took first and second place. But, because Daniel Ricciardo's Red Bull car has been effectively bulletproof (he's been forced to retire from just one race and that was because of human error during a pit stop), consistency has kept him in the fight. If Mercedes continues to have reliability problems through the remainder of the season, Ricciardo could snatch the championship at the last race in Abu Dhabi.