We report a quantum scattering calculation of energy transfer and collision-induced dissociation of HCO in collisions with Ar. The HCO rotation is treated in the infinite order sudden approximation, and the HCO vibrations are treated by the coupled-channel method. Sixty L(2) HCO vibrational wave functions are included in the coupled-channel basis, of which 15 correspond to bound HCO states for zero HCO angular momentum, and the remainder represent a discretized continuum, which includes ten resonances. A simple "sum-of-pairs" potential is used to describe the Ar-HCO interaction, and the HCO intramolecular potential is the previous Legendre polynomial fit to ab initio calculations. Vibrational state-specific and state-to-state cross sections, averaged over the orientation of Ar relative to the GO-bond axis, are calculated over a range of translational energies. Collision-induced dissociation cross sections to form H+CO from all HCO bound states are presented, and decomposed into components corresponding to dissociation via HCO resonances and dissociation via nonresonance states. The energy transfer from selected initial states is also calculated as a function of initial relative translational energy.