A CP-violating interaction of the nuclear magnetic quadrupole moment (MQM) with electrons in the ytterbium monohydroxide molecule YbOH173 is considered. Both the MQM of the Yb173 nucleus and the molecular interaction constant WM are estimated. Electron correlation effects are taken into account within the relativistic Fock-space coupled-cluster method. Results are interpreted in terms of the strength constants of CP-violating nuclear forces, neutron dipole moment (EDM), QCD vacuum angle θ, quark EDMs, and chromo-EDMs.