A γ-ray spectroscopy study of excited states in Si26 has been performed by using the Mg24(3He,n) reaction at a beam energy of 10 MeV. In particular, states have been studied above the proton threshold relevant for burning in the Al25(p,γ)Si26 reaction in novae. This reaction influences the amount of Al26 injected into the interstellar medium by novae, which contributes to the overall flux of cosmic γ-ray emission from Al26 observed in satellite missions. The present results point strongly to the existence of a 0+ state at an excitation energy of 5890 keV lying within the Gamow burning window, which raises questions about the existence and properties of another, higher-lying state reported in previous experimental work. The existence of two such states within this excitation energy region cannot be understood within the framework of sd-shell-model calculations.