I have a full carbon bike with about 1500 miles us use. The cranks appear to be carbon also. When I work the cranks hard, i.e. standing up, going uphill, I hear a creaking sound coming from the cranks. When I pedal in steady state, I do not hear the creaking. Is the creaking sound normal? If the sound indicates a problem, is it fixable?
Creaking can often be fixed. Fixing it tends to be a process of elimination. The first few things I'd look at are
1. grease the pedal threads liberally and ensure they're pretty tightly installed
2. confirm your cranks are properly tightened to their axle
3. confirm that your rear wheel is fastened quite securely... I've fixed quite a few customers' creaks just by lubricating their rear wheel's quick-release cam and tightening it adequately.
Those are relatively easy. The next phase would be to remove the cranks and bottom bracket, grease up all the contact surfaces and threads, reinstall properly and test again.