A programming error involving Formula 1’s complex 2026 power units delayed the start of the Bahrain Grand Prix in Malaysia. Some paddock insiders described it as a perfect storm, with a chain of factors that came close to shutting down several power units. The problem originated in the parameters governing the use of electrical power in wet conditions, which the FIA was forced to adjust to ensure the combustion engine could continue operating correctly.
How the Sepang power unit bug developed
The trigger was the storm that hit Sepang around the time of the start, setting off a chain of events that exposed a bug in the power unit control software. Following the prescribed procedure, and for the first time since the current technical regulations were introduced, Race Control declared a low-grip conditions scenario, which activates different rules governing power unit use. In particular, the maximum output of the electric motor drops from 300 to 250 kW, with a further reduction in the more technical sections of the circuit.
One of those areas is around Turn 9, the hairpin at the end of the second sector and one of the slowest sections of the Malaysian circuit. Max Verstappen, leading the field on the formation lap after taking pole position on Saturday, slowed to below 50 km/h. This caused the combustion engine revs to fall and also slowed the turbo, resulting in a loss of boost pressure.
At that point, the restrictions on electrical power in wet conditions meant the electric motor could no longer provide enough assistance to raise the combustion engine’s revs and bring the turbo back up to pressure. The power unit therefore entered a negative spiral in which it continued to lose power until a bug in the control software was triggered.
The software bug that left F1 cars without power
The electronic control unit is believed to have entered a mode known as Continuous Offset, which prevents use of the electric motor for one minute. This condition is triggered when the electrical component is switched off suddenly rather than progressively, a scenario permitted by the regulations only for safety reasons.
By disabling the MGU-K for 60 seconds, the system discourages anyone from abruptly switching it off for performance purposes, as had happened with the solution developed by Mercedes- and Red Bull-powered cars in qualifying earlier in the year. PlanetF1 offered a different reconstruction, according to which the power units entered a protective failsafe mode.
Whichever mode was actually activated, the practical consequence was the same: throttle input became effectively useless. Telemetry shows Max Verstappen repeatedly pressing the accelerator, visible through the repeated throttle-input spikes, without the car ever accelerating beyond 40 km/h.
At a certain point, the Red Bull power unit managed to reset itself and returned to normal operation. By then, however, the long period during which Max Verstappen had been travelling at low speed had forced the drivers behind him to slow as well, including both Ferrari drivers, triggering the same negative spiral.
The telemetry indicates that Charles Leclerc somehow managed to recover from the situation, while Lewis Hamilton had to stop his Ferrari and restart the power unit to allow the entire system to reset. The unusual sequence became one of the defining moments of the Sepang software chaos before the race could eventually begin.
How the FIA intervened before the Bahrain GP start
The slowing cars at the front progressively forced the rest of the field to do the same, causing the problem to appear on cars powered by Ferrari, Red Bull, Mercedes and Audi engines, with no apparent correlation to the characteristics of the individual power unit designs. At that point, the FIA recognised the software bug, which had been developed by the governing body itself in collaboration with the teams.
The start therefore had to be delayed by another 20 minutes while the FIA’s technical department corrected the control software code. According to the statement subsequently issued by the governing body, the new version removed the limits on usable energy in the affected sectors. The emergency Sepang software update was then distributed so the teams could apply the changes before the start.
However, a more plausible interpretation reported by several members of the media was that the limits on electrical power had been relaxed, allowing greater use of the electric component to keep the combustion engine operating at sufficiently high revs.
Nikolas Tombazis explains the unprecedented Sepang scenario
FIA single-seater director Nikolas Tombazis addressed what happened directly: “We were not able to test the software as extensively as we would have liked, because we have done very little running in the wet this year and there was a combination of circumstances that triggered this bug. Essentially, during the formation lap, some cars were travelling very slowly, almost coming to a stop. This caused a chain reaction between the cars and some of them almost stopped completely. The bug prevented the power unit from delivering the power needed to get moving again.”
Nikolas Tombazis added: “Once the problem occurred, our staff quickly understood what was happening, under significant time pressure to update the software so that the teams could install it on their cars. All of this took 20 minutes. It may have felt like five hours for the spectators, which is understandable and we are sorry about that. However, considering the problem, I think it was a quick response.”
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