Context : The nucleus of the planetary nebula Hen 2-428 is a short orbital-period ( 4.2 h ) , double-lined spectroscopic binary , whose status as a potential supernova type Ia progenitor has raised some controversy in the literature .

Aims : With the aim of resolving this debate , we carried out an in-depth reanalysis of the system .

Methods : Our approach combines a refined wavelength calibration , thorough line-identifications , improved radial-velocity measurements , non-LTE spectral modeling , as well as multi-band light-curve fitting .
Our results are then discussed in view of state-of-the-art stellar evolutionary models .

Results : Besides systematic zero-point shifts in the wavelength calibration of the OSIRIS spectra which were also used in the previous analysis of the system , we found that the spectra are contaminated with diffuse interstellar bands .
Our Voigt-profile radial velocity fitting method , which considers the additional absorption of these diffuse interstellar bands , reveals significantly lower masses ( M _ { 1 } = 0.66 \pm 0.11 M _ { \odot } and M _ { 2 } = 0.42 \pm 0.07 M _ { \odot } ) than previously reported and a mass ratio that is clearly below unity .
Our spectral and light curve analyses lead to consistent results , however , we find higher effective temperatures and smaller radii than previously reported .
Moreover , we find that the red-excess that was reported before to prove to be a mere artifact of an outdated reddening law that was applied .

Conclusions : Our work shows that blends of He ii \lambda 5412 Å with diffuse interstellar bands have led to an overestimation of the previously reported dynamical masses of Hen 2-428 .
The merging event of Hen 2-428 will not be recognised as a supernova type Ia , but most likely leads to the formation of a H-deficient star .
We suggest that the system was formed via a first stable mass transfer episode , followed by common envelope evolution , and it is now composed of a post-early asymptotic giant branch star and a reheated He-core white dwarf .