Heavy neutrino searches and NA62 status

The NA62 experiment at CERN SPS recorded in 2007 a large sample of $K^+\to\mu^+\nu_\mu$ decays. A peak search in the missing mass spectrum of this decay is performed. In the absence of observed signal, the limits obtained on $\mathcal{B}(K^+\to\mu^+\nu_h)$ and on the mixing matrix element $|U_{\mu4}|^2$ are reported. The upgraded NA62 experiment started data taking in 2015, with the aim of measuring the branching fraction of the $K+\to\pi^+\nu\bar{\nu}$ decay. An update on the status of the experiment is presented.