The little yellow horseshoe with an exclamation point is lit. This is an indicator one or more of the tires have a low air pressure condition, if the light is on solid. If the light is flashing, that indicates a failure within the tire pressure monitor system. In either case, examine your tires, test and ensure the air pressure in all tires is properly set and then proceed to your service provider. A tire may need repaired or testing may need completed to determine where the system fault is located.