EPA is taking final action to make nonconformance penalties (NCPs) available to manufacturers of heavy heavy-duty diesel engines in model years 2012 and 2013 for emissions of oxides of nitrogen (NO<INF>X</INF>). In general, the availability of NCPs allows a manufacturer of heavy-duty engines (HDEs) whose engines fail to conform to specified applicable emission standards, but do not exceed a designated upper limit, to be issued a certificate of conformity upon payment of a monetary penalty to the United States Government. The upper limit associated with these NCPs is 0.50 grams of NO<INF>X</INF> per horsepower-hour.