We investigate a reliability of conservation of the vector current (CV) hypothesis in the neutron β−-decay. We calculate the contribution of the phenomenological term, responsible for the CVC in the hadronic current of the neutron β−-decay (or the CVC effect), to the neutron lifetime. We show that the CVC effect increases the neutron lifetime with a relative contribution 8.684×10−2. This leads to the increase of the neutron lifetime by 76.4 s with respect to the world averaged value τn=880.2(1.0)s (Particle Data Group, Chin. Phys. 40, 100001 (2016)). We show that since in the Standard Model (SM) there are no interactions, which are able to cancel such a huge increase of the neutron lifetime, we have to turn to the interactions beyond the SM the contribution of which to the neutron lifetime reduces to the Fierz interference term bF only. Cancelling the CVC effect at the level of the experimental accuracy we get bF=0.1219(12). If this value cannot be accepted for the Fierz interference term, the CVC effect induces irresistible problems for description and understanding of the neutron β−-decay.
