Alonso crashed out on the opening lap in Spielberg in a collision with Ferrari’s Kimi Raikkonen, while Button retired soon after with a sensor failure issue. As a result, both drivers face uncertainty over their Honda power units for the British team's home race.
“We have completed thorough checks of both power units back at the factory, and we believe that Fernando's power unit has sustained damage from the accident,” said Yasuhisa Arai, Honda R&D senior managing officer - chief officer of motorsport.
“It may be necessary to change the engine. As for Jenson's power unit this weekend, the issue is still under investigation.”
Alonso and Button were hit with a combined 50-place grid drop in Austria after taking on their fifth engines of the year - regulations permit only four - as well as other new power unit elements.
A sixth engine for either at Silverstone would mean another 10-place grid penalty, hence the team are instead expected to revert to a previously-used unit should a change be needed.
“Honda is not looking to put any hardware updates in place for the British Grand Prix, but we will optimise the power unit setting to the updated aero parts planned on the chassis,” added Arai.
Despite their problems in Austria, McLaren did at least have a productive post-race test in Spielberg, clocking up almost 800 km of trouble-free running with the MP4-30.
“We completed a solid and varied test programme to arm us with a lot of useful information,” reported racing director Eric Boullier. “We evaluated a number of different aero components, which so far have shown positive signs, so we’ll continue testing their effectiveness at Silverstone this weekend as we seek to continue improving our performance.”
Alonso and Button have recorded just six race finishes between them this season, with the latter’s eighth place in Monaco the team’s only point-scoring result of the year to date.