If it is on, there is a reason.
The Check Engine/Service Engine Soon light comes on the dash when there is an emissions related failure. Be sure to take this seriously. This light does not mean that you just need an oil change or routine maintenance. There are many different systems/component failures that may cause this light to come on! Your vehicle will need to be taken to the repair shop for diagnostic work.
If the light stays on solid, don’t panic, call your repair facility and set up an appointment to determine the reason the light is on. Do this at your earliest possible convenience. If your check engine light is on solid, and the vehicle is running rough, you want to get to your repair shop as soon as possible.
If the light is flashing, this means things are slightly more serious. Also, get your vehicle to your repair facility ASAP to prevent the risk of more damage. If the light is blinking and the engine is running rough, stop the vehicle immediately to prevent potential serious damage. Arrange for your vehicle to be towed to your repair facility.