The FIA has warned teams running with off-throttle blown diffusers at the Spanish Grand Prix that there is a risk of them being subject to a protest this weekend.
Although motor racing's governing body decided to hold back on a move to immediately outlaw teams from pumping gases through their blown diffusers when drivers were off the throttle, it has not wavered from its belief that the practice is against the regulations.
FIA technical delegate Charlie Whiting said in a media briefing on Friday that although the governing body would not act to disqualify cars this weekend, it could not rule out a team not running such off-throttle blown diffusers - like Williams, Virgin Racing and HRT - from protesting.
"It is always a possibility," said Whiting. "I've made that clear to the teams that it could happen and then we will take it to the stewards in the normal way.
"We have always maintained in all of our technical directives that we have sent for many years now that this is merely the opinion of the technical department, and anyone is free to challenge it in front of the stewards. It doesn't happen very often but it has happened in the past. As you know with the brakes in Brazil, for example, in 1998.
"But it can happen and I've told the teams that were pleased that we decided to postpone this introduction that it could happen."
When asked if there was the chance, then, that the FIA would have to disqualify the majority of the grid, Whiting said: "I would like to think that that probably wouldn't happen, but one never knows. It is not beyond the realms of possibility. A protest is open to anybody as you know, then it will go before the stewards."
Whiting said that the FIA had decided to act on off-throttle blown diffusers because it was worried about how extreme some solutions were becoming.
"It became apparent to us through examination of data that what we thought was a fairly benign feature was turning into something that was being used, in our opinion, illegally," explained Whiting.
"An exhaust system is there for the purpose of exhausting gases from the engine, so when you are off throttle it is not doing that - therefore driver movement is being used to influence the aerodynamic characteristics of the car.
"We were becoming increasingly concerned about the increase in extremes, shall we say. Then a bit of fuel, a bit of spark, retard, it was getting more and more extreme and that was the main reason for it."
He added: "These things start off little and start off appearing to be quite benign, but then they get worse and worse and worse. And we are now faced with the possibility of even more extreme systems coming along, so we felt it was time to do something about it.
"Of course exhaust blowing is not new, it has been around for years, but I think Red Bull really took it to another plain with their low exhaust at the beginning of last year, and it became clearer and clearer through engine mapping that it was time to do something about it.
"It got more and more and more extreme. It is by no means unusual - these things happen. It happened with brake ducts for example and aerodynamic appendages on brake ducts, and in the end you realise you have to do something about it. So, it was really not at all unusual."
And amid suspicions that the FIA acted after a complaint from a team not running an off-throttle blown diffusers, Whiting said: "We often do react if a team writes to us about something.
"They will ask us to circulate that correspondence in order to flush out what other teams might be doing. That was the case [in this instance], but the team concerned did not want us to divulge who it was."