We present a preliminary study oriented to evaluate the sensitivity of the latest Planck 2015 data release to non-standard self interacts of neutrinos. We consider the case of massless neutrinos whose interaction is mediated by a massless pseudoscalar boson. In this scenario neutrinos decouple form the rest of the primordial fluid as described in standard cosmology, but later, depending on the strength of the interaction, recouple and start to scatter among themselves.
This behaviour leaves an imprint on the angular power spectra (APS) of the cosmic microwave background (CMB), moreover the 2015 Planck release includes the high-$\ell$ polarization data which can improve the constraint on the coupling constant $g_{\mathrm{rm}}$ of the secret interaction.
The possible improvement in constraining the strength of the new interaction seems to be important and worthy of being thorough.