Toro Rosso drivers Pierre Gasly and Brendon Hartley are to use Honda’s previous specification power unit at this weekend’s Mexican Grand Prix.
Honda introduced its Spec 3 power unit in Russia and ran it throughout the events in Japan and the United States, with both drivers buoyed by the progress made with development.
However, Honda says it has a "better understanding" of its previous spec power unit in order to deal with the higher altitude conditions found at the Autodromo Hermanos Rodriguez, which lies over 2,000 metres above sea level.
Honda has nonetheless used the opportunity to take on fresh Spec 3 components for Gasly’s car for FP1, meaning the Frenchman will take a 15-place penalty, effectively relegating him to the back of the grid.
Gasly has taken on a new MGU-H, turbocharger and Internal Combustion Engine – his eighth of the season for all three components.
Honda chief Toyoharu Tanabe confirmed that the manufacturer had “a concern regarding the assemble of the [power unit] used in Austin.
“That PU has been sent to Sakura for a full inspection and, at the moment, we are not sure if we can use it again this year.
“By fitting a new one here we add one to the pool of available units for the rest of the season.
“However, as from FP2, and for the rest of the weekend, Gasly will run an older specification PU. Brendon is also using this spec, for the entire weekend.
“The reason for reverting to the earlier pre-Russia spec is that we have a better understanding of this version of the PU and are more confident in our ability to set it up correctly for the specific conditions here in Mexico City.”
Honda is ramping up development through the latter stages of 2018 ahead of its partnership with the front-running Red Bull team for 2019.
Toro Rosso currently holds eighth position in the Constructors’ Championship, four points clear of Sauber.
