Formula 1's governing body moved to close a suspected loophole in the new engine regulations on Wednesday by proposing a change from August.
The FIA said in a statement that it had recently launched an e-vote on changing the assessment of the power unit compression ratio in running condition.
It said that from August 1, compliance with the limit "must be demonstrated not only at ambient conditions but also at a representative operating temperature of 130 degrees Celsius".
The subject has been a major talking point in the pre-season, with Mercedes – who insist their engine is completely legal – suspected of exploiting a loophole to gain performance through thermal expansion of components.
Mercedes supply engines to champions McLaren as well as their own works team, Williams and Renault-owned Alpine.
If the proposal is accepted for August, that would still give them and customer teams the first 13 races of the 24 round season before any change.
Red Bull, who are now making their own engines, also supply sister team Racing Bulls. Audi, Honda (Aston Martin) and Ferrari are the remaining engine manufacturers.
Team boss Laurent Mekies said on Wednesday he welcomed clarity.
"We don't think it's noise," he said, after Williams chief James Vowles had used that expression.
"It's true that it is early days, but it will come along very quickly where it's a competitive advantage – whether its one, two, three whatever number of tenths is going to make a difference."
The FIA's Formula One commission also discussed issues that have emerged from testing the new cars, with the sport undergoing a major revamp to the chassis rules.
"Further evaluation and technical checks on energy-management matters will be carried out over the following three days at the second pre-season test in Bahrain," the statement said.