O [Formula Presented] single-hole ionization cross sections of CO have been measured for [Formula Presented] The O [Formula Presented] shape resonance moves up in energy with an increase in [Formula Presented] opposite to the C [Formula Presented] shape resonance observed previously. Theoretical calculations beyond the fixed-nuclei approximation reproduce these experimental results. The relationship between the [Formula Presented]-dependent characteristic internuclear distance in the residual ion and the shape resonance energy is discussed.