Honda are investigating the problem with their engines and decided not to send Button or Barrichello out in case they need to revert to an older engine spec without a penalty.
Honda's Sporting Director Gil de Ferran said:
Obviousy we had a difficult day with, unusually, two failures occurring very early on in the life of each engine in Anthony's car. Since they were totally unexpected, we elected not to run the race cars until we could gain a better understanding of what was causing them. Needless to say this has not been the best start to the weekend for us as we collected very little data today about cars and tyres, however thankfully we were testing here a week ago so the set-up of the car and tyre choice are more dialled-in than they would otherwise be. We look forward to a better day tomorrow.