The FIA has issued updated technical guidance to outlaw a smart qualifying trick used by Mercedes and Red Bull during the opening phase of the 2026 Formula 1 season.

According to a report from The Race, both teams found a way to gain extra speed on the final metres of a qualifying lap by exploiting a grey area in the new hybrid power unit regulations.

Under the standard rules, electric power deployment from the MGU-K must gradually reduce by 50kW per second as a car approaches the timing line. However, Mercedes and Red Bull reportedly discovered a method that allowed them to keep maximum deployment for longer before switching the system off instantly just before the line.

That gave them a small but important straight-line advantage worth valuable hundredths of a second in qualifying, where margins are often extremely tight.

The system worked because the emergency MGU-K shutdown triggered a mandatory 60-second lockout period. In race conditions, that would be highly damaging, but at the end of a qualifying lap it had little consequence, as drivers were immediately entering a cool-down lap where full deployment was not needed.

The emergency shutdown function was originally introduced to protect components in the event of a technical issue, not as a performance tool. The FIA has now clarified that it must only be used in genuine emergency situations.

Safety concerns also played a role in the decision. During the Japanese Grand Prix weekend, Kimi Antonelli and Max Verstappen both suffered sudden power losses that left them running slowly through corners, while Alexander Albon was forced to stop during practice after complications linked to the system.

The Race also reported that Ferrari raised concerns over the safety and fairness of the tactic.

With the loophole now closed, another controversial interpretation of the 2026 rules has been removed, and rivals will hope qualifying battles become even closer in the races ahead.