The FIA has announced a decision which it hopes will put works and customer teams on equal footing with regard to engine performance.
While Formula 1's technical rules stipulate that all power units supplied to a manufacturer to its customers must be identical to the engine used by a works team, the regulations failed to stipulate that the same equality applied to how the units were operated.
The governing body suspected works teams of unlocking specific modes, in qualifying trim for example, to gain a power advantage to which customer teams may not have access.
Engine equality is covered by a dossier system included in Appendix 4 of the sporting rules. Last month, the FIA sent a technical directive to F1 teams in which it noted that, while the purpose of Appendix 4 is to ensure that all power units supplied by one manufacturer are identical in all respects, it had good reason to believe that this may not be the case.
"Whilst the dossiers for each team may be identical it would appear that some are being operated in a different way to others being supplied by the same manufacturer," the FIA specified in its directive.
"It is therefore our view that all power units supplied by one manufacturer should be identical, not only in terms of the dossier for each team being the same, but we also feel they should be operated in an identical way.
"With this in mind, we will expect all power units supplied by the same manufacturer to be:
"i) Identical according to the dossier for each team.
"and, unless a team informs us that they have declined any of the following, they should be:
"ii) Run with identical software and must be capable of being operated in precisely the same way.
"iii) Run with identical specifications of oil and fuel."
In the last two years, Ferrari was allowed to supply older spec engines to its customers, Toro Rosso in 2016 and Sauber last year. This season however, all teams will be running current-spec power units.