  A search for lepton flavour violating decays of a neutral non-standard-model
Higgs boson in the $\mu\tau$ and e$\tau$ decay modes is presented. The search
is based on proton-proton collisions at a center of mass energy $\sqrt{s} =$ 13
TeV collected with the CMS detector in 2016, corresponding to an integrated
luminosity of 35.9 fb$^{-1}$. The $\tau$ leptons are reconstructed in the
leptonic and hadronic decay modes. No signal is observed in the mass range
200-900 GeV. At 95% confidence level, the observed (expected) upper limits on
the production cross section multiplied by the branching fraction vary from
51.9 (57.4) fb to 1.6 (2.1) fb for the $\mu\tau$ and from 94.1 (91.6) fb to 2.3
(2.3) fb for the e$\tau$ decay modes.
