Ahead of the German Grand Prix, the FIA confirmed that a complete new Honda power unit has been fitted to Gasly's car. The changes include his fifth engine, turbocharger and MGU-H, his fourth MGU-K and third energy store and control electronics.
The result is the maximum 15-place grid penalty for the Frenchman, as all the component changes have exceeded his limit for the season, and he now faces an uphill battle to bring home much-needed points on Sunday.
Honda explained: "Prior to today's race, for tactical reasons, we are changing all PU elements with the exception of battery-related components on Pierre's car."
Gasly - who dropped out of the points at Silverstone after being handed a five-second penalty - was 16th on the provisional grid but he now starts behind team mate Brendon Hartley, Williams’ Lance Stroll and McLaren’s Stoffel Vandoorne.
Riccardo was handed a grid penalty on Friday after Red Bull also opted to change a number of power unit components on his car.