The FIA will attempt to clamp down on rumoured fuel-flow sensor trickery next season, with a recent technical directive issued this week requiring all teams to run a second sensor.
Speculation that Ferrari in particular were tricking the fuel-flow sensor to deliver more fuel than the rules allow – a rate of 100kg/h – heightened ahead of the United States Grand Prix when Red Bull approached the FIA with questions over the legality of such a system.
It's thought – though hasn't been proven – that Ferrari is using electrical interference to bypass the flow rate of the sensor and following Red Bull's highlighting of this, the FIA issued a technical directive clarifying such a practice would contravene the rules.
Ferrari were then off the pace in Austin and the following race in Brazil, prompting some to suggest this was a result of the clarification and thus proving the Italian team were breaking the rules.
Ferrari deny this and insist its drop in performance is down to a number of factors.
Following the Brazilian GP, the FIA confiscated three fuel systems – one is believed to have come from Ferrari, one from a Ferrari customer team and one from a non-Ferrari powered car – in order to investigate further.
This latest technical directive, issued on Wednesday ahead of the season finale in Abu Dhabi next weekend, mandates a second fuel-flow sensor must be fitted from next season and will be controlled exclusively by the FIA.
Due to the work involved in fitting this and the short timeframe, it won't apply to the final round of the 2019 season.