If only this symbol is appearing, then its not exactly Emission Control system.
It is "Check Engine", means there is some problem with any sensor of the engine. It may include any of the sensor. so now you need to goto some car shop where he can diagnose the error. or if you have any OBD-II adapter then you can check yourself.
Please tell what if you have done anything before this Check Engone light comes on, any car wash or anu other maintenance etc. ?