A cold start NO2 generation system includes a catalyst control module that identifies a portion of a three-way catalyst that corresponds to a nitrogen dioxide zone. A diagnostic module determines a temperature in the nitrogen dioxide zone, and a fuel control module adjusts an air/fuel ratio based on the temperature in the nitrogen dioxide zone. A cold start NO2 generation method includes identifying a portion of a three-way catalyst that corresponds to a nitrogen dioxide zone. The method further includes determining a temperature in the nitrogen dioxide zone and adjusting an air/fuel ratio based on the temperature in the nitrogen dioxide zone.