Although diesel vehicles have high energy efficiency, the removal of emitted NOx at low temperature persists as an important issue. This report presents an examination of low-temperature NOx removal using ozone injection and a plasma-lean NOx trap (LNT) catalyst system. Ozone is readily producible by a dielectric barrier discharge reactor using oxygen in air, and its injection to emitted NO enables oxidation to NO2 even at low temperatures. Results show that synergetic effects of ozone injection and plasma-LNT catalyst system enable low-temperature NOx removal.