  We study the effect of a single impurity on the transport properties of a one
dimensional quantum liquid highly excited away from its ground state by a
sudden quench of the bulk interaction. In particular we compute the time
dependent dc current to leading order in the impurity potential, using
bosonization and starting both from the limit of a uniform system and from the
one of two decoupled semi-infinite systems. Our results reveal that the
nonequilibrium excitation of bulk modes induced by the global quench has
important effects on the conductor-insulator quantum phase transition, which
turns into a crossover for any small quench amplitude. In addition, the
dynamics of the current displays a faster decay towards the steady-state as
compared to the equilibrium case, a signature of quench-induced decoherence.
