Honda will deploy their final four development tokens on an upgraded engine which Fernando Alonso will run at this weekend's Russian GP.
The Japanese manufacturer, who have endured a torrid return to F1 with McLaren this year, had four tokens left unspent following previous performance upgrades in Canada and Belgium.
However, those tokens have now all been used up ahead of the Sochi race to improve the core internal combustion engine - although only Alonso will run the unit this weekend owing to tight manufacturing deadlines.
"We have used the remaining tokens [four] on ICE upgrade, to improve the combustion characteristics of the engine," a Honda spokesperson said.
"Due to manufacturing timeline, it was only possible to apply one car with an updated engine. Based on past usage of the ICE, the team has decided to apply this on car 14 [Alonso]."
With both McLaren drivers having already used nine ICEs this season, the upgrade for Alonso will automatically trigger a 10-place penalty for a 10th engine, with more penalties possible should other fresh power unit elements be fitted.
Given McLaren-Honda's uncompetitive form in 2015 - the revived partnership have scored just 17 points so far - the penalty will almost certainly mean Alonso starts at the back of the field on Sunday.
Jenson Button stays with the same engine McLaren unlocked at Monza and means he will start where he qualifies unless he picks up subsequent penalties.
Honda join Mercedes in using up their allocation of tokens for 2015, with Ferrari left on four and Renault 12 - the same number as Red Bull's supplier started the season with.
At Honda's home race in Japan two weeks ago, Alonso was heavily critical of the engine maker's product in a series of outbursts over team radio - labelling the team's lack of pace down the straights "embarrassing" and likening it to having a "GP2 engine".
Don't miss Sky Sports F1's live weekend-long coverage of the 2015 Russian Grand Prix. Our race-day show begins at 10.30am on Sunday, with lights out at 12 noon. Watch the Russian GP for £6.99 with NOW TV