Abstract: An engine control system including an engine configured to generate exhaust comprising an exhaust constituent and to operate in a first operating mode or a second operating mode different from the first operating mode. The engine control system can include a plurality of sensors configured to generate temperature data corresponding to at least one of a measured exhaust temperature and an ambient temperature, and exhaust constituent data corresponding to an exhaust constituent concentration. The engine control system can include a controller operatively coupled to the plurality of sensors and the engine, and configured to receive the temperature data and the exhaust constituent data from the plurality of sensors, and change an operating state of the engine from the first operating mode to the second operating mode when the temperature data is less than a predetermined temperature threshold and the exhaust constituent data is greater than a predetermined exhaust constituent threshold.