Renault Megane 1.4E engine symbol red light on dash

That's a check engine light, the engine on your car has several sensors installed on different parts of engine and drivetrain, any time any of them senses a problem that red engine light come on on the dash, the way to know what's the problem is to take it to an auto place or buy an OBD ( On Board Diagnostic) tool and connect it to the connector located underneath the dashboard, the scanner will get the code and by looking up that code you'll find out what part of the car has problem. You can continue using your car and some times these problems are not very major ( emissions control related) but if that light starts blinking that's the time you should seriously consider having a look at it. Hope I could help you and please rate the answer if it was helpful, it effects my general rating, thanks very much!