McLaren are unsure about the cause of their power unit-related problems which left Oscar Piastri and Lando Norris unable to start the Chinese Grand Prix.

Piastri and Norris were due to start on the third row of the grid but two unrelated problems with the same power unit component left both drivers to watch the race from the paddock.

It means Piastri is yet to complete a Grand Prix racing lap, having crashed out of his home event in Australia, while Norris suffered his first career DNS.

McLaren boss Stella confirmed the team's engine supplier, Mercedes, are looking into what led to McLaren's first double failure to start since the 2005 United States Grand Prix.

"We came here to go racing and today we were not in condition to do so due to technical problems. This is very frustrating and disappointing for the team, drivers, our technical and commercial partners and the fans," Stella told Sky Sports F1.

"We are sorry for that. We will regroup, understand the technical problems and go again in Japan. Once we were preparing the car of Lando, to leave the garage, we found a problem on the electrical side of the power unit. We tried to fix it but there was no way to fix it.

"Once we were on the grid, we found another problem, on the electrical side of the power unit on Oscar's side. They seemed to be different problems occurring at the same time and they basically meant there was no way to start the race.

"Something that is an extremely unfortunate coincidence of two different problems on the electrical side of the power unit, appearing at the same time. But that's what it is.

"We go as one team. We will investigate together with HPP [Mercedes High Performance Powertrains] and we will see what the learning is and make sure it doesn't happen again."

It has been a challenging start to Norris' title defence, while McLaren are also aiming for a third straight constructors' title.

McLaren appear to be around half a second slower than pace-setters Mercedes but have shown in recent years they are capable of outdeveloping their rivals over a season.

Stella says that while further track time to gain more data would have been useful, the lost opportunity to score more points is more "detrimental".

"While at the moment Mercedes seem to be in their own category and we are a little closer to Ferrari, we obviously race with the ambition to compete for important results," he said.

"We are just losing ground. These points could be important at the end of the season, so the most important shortcoming of what happened today is not scoring the points.

"At the same time, it's also quite regrettable and disappointing for our fans, for our partners from a commercial and a technical point of view, so there are obviously several downsides.

"Every lap is important in 2026. At the same time, I think we are learning quite rapidly. And with what we have learned in Australia, in the China sprint, we think we are actually in a good position now in terms of especially exploiting the power units."

Formula 1 next heads to the iconic Suzuka Circuit for the Japanese Grand Prix on March 27-29 live on Sky Sports F1. Stream Sky Sports with NOW - no contract, cancel anytime