The FIA has issued a clarification in the wake of the Red Bull engine mapping row in Germany, and the Milton Keynes-based team will now have to make changes ahead of this weekend's Hungarian Grand Prix.

Red Bull was referred to the German Grand Prix stewards on Sunday after F1 technical delegate Jo Bauer discovered an issue regarding the engine maps of the cars of Sebastian Vettel and Mark Webber. Bauer's statement revealed that a reduced torque level in the mid rpm ranger had been found which he deemed to be a breach of the technical regulations [see separate story - HERE].

Although the stewards disagreed and took no action [see separate story here - HERE], the FIA has now moved to close the perceived loophole and remove any ambiguity.

According to reports by BBC Sport the new rule asks teams to 'nominate any one engine map used in the first four races of the season as a reference map'.

"Above 6,000rpm, the maximum engine torque may vary by no more than +/- 2% (from the reference map)," the clarification reads, "and the ignition angle may vary by no more than 2.5%."

McLaren managing director Jonathan Neale meanwhile admitted he is not sure how much the changes will affect Red Bull.

"That is a really interesting question and the honest answer is I really don't know," he said speaking during the latest Vodafone McLaren Mercedes phone-in before confirmation of the clarification was made public.

"None of us really know what it is that antagonised the FIA so much to provoke Jo Bauer in to issuing the note that he did on Sunday morning. It was quite an unusual step, but I don't think the FIA would have referred it to the stewards if they didn't have very serious concerns.

"I've read the press like you have and there are lots of allusions to the fact that there might be some action taken to outlaw it but I haven't seen that. It's impossible for us to tell exactly what their engine is doing and therefore how much advantage they get from it on their car.

"I know we're not the only ones on the grid who are looking at it very carefully and I think we've all worked really hard through the first six months of this year to work with the FIA and with Charlie Whiting to be really clear about what is acceptable and what isn't. And I pledge that support again to Charlie and the FIA. I think they've got a very difficult job there; they did a good job early on.

"I hope that we don't get in to lots of rewriting of the exhaust regulations for the season as we did last year because that provided a reasonable amount of upset and difficulty no matter how entertaining it was for the press and the media at Silverstone last year.

"In terms of us - the teams - and the sport, I think consistency in regulation is good. We need to put a lot more effort into enforcing those regulations rather than continually rewriting."