How a software bug left F1 cars stranded before the wet-weather start

Heavy rain delayed the start of the Formula 1 Grand Prix in Malaysia by 40 minutes. When the field finally set off for the formation laps, several cars crawled around the circuit or stopped, forcing officials to abandon the start and extend the delay by more than 45 minutes.

Why the cars lost power

Wet-weather running uses an alternative engine mode that limits energy deployment to 250kW, rather than the 350kW maximum available in dry conditions. In certain sectors, a further 250kW reduction is imposed for safety reasons. One of those areas is the Turn 9 left-hander at Sepang, where the problems emerged.

At Turn 9, the electric power does not need to ramp down gradually, allowing the MGU-K to shut off instantly. As cars slowed dramatically behind the safety car, boost pressure fell. With no MGU-K power available to help, a software fault placed cars into “continuous offset” — a 60-second emergency lockdown designed to prevent teams from deliberately shutting down the MGU-K. The mode could also cut power from the internal combustion engine.

The complexity of the 2026 power-unit systems has already drawn scrutiny; this incident showed how their interacting settings could combine in conditions that had not been tested. F1’s 2026 rule changes provide broader context for the new power modes and other regulation changes.

The FIA’s technical department responded by removing the 250kW constraint in the affected sectors through an updated software release. Teams installed the update during the rain delay, restoring enough MGU-K power for cars to circulate at low speed.

Why testing did not catch it

FIA single-seater director Nikolas Tombazis said limited wet running meant the software had not been tested as extensively as intended. The 2026 cars had encountered wet conditions at a small number of tyre tests, but Tombazis said those sessions did not reproduce the extremely slow formation-lap speeds at Sepang.

The software was developed collaboratively by the FIA, the standard ECU supplier, teams and power-unit manufacturers. Tombazis acknowledged that the emergency update was rushed, but said the issue was identified quickly and the revised code was distributed in about 20 minutes.

The FIA and teams will conduct a full review. Tombazis said the specific problem should not recur, while cautioning that he could not guarantee there would never be another software issue in systems combining electrical and combustion power. He described the incident as a lesson for the sport: “Sometimes things fall through the net and people learn, and you do a better job next time.”