A stop/start vehicle includes an engine and a stop/start system that selectively prevents an auto stop or auto start of the engine in response to a detected vehicle proximity and direction of travel relative to an emergency vehicle. The stop/start system may be programmed to prevent an auto stop of the engine in response to a detected proximity to an emergency vehicle where the emergency vehicle is traveling in the same direction as the stop/start vehicle, or in response to a detected proximity to an emergency vehicle where the stop/start vehicle is located within an intersection. The stop start system may also be programmed to prevent an auto start of the engine in response to the engine being stopped, and further in response to a detected proximity to an emergency vehicle where the emergency vehicle is traveling in cross traffic relative to the stop/start vehicle.