EML light went on. What is this?

Engine Management Light, same as a Check Engine Light... simply means a sensor component on your vehicle is malfunctioning You'll need to have someone with a tester to run diagnostics and retrieve codes to find exactly what the culprit is. Don't be surprised if it's the Throttle Positioning Sensor (TPS), common problem on BMWs

The EML light is NOT the check engine light on a BMW as Mr. Schulze described, it is the electronic engine output control light. EML is an acronym for "Elektronische Motorleistungsregelung". Loosely translated from German means Electronic Engine Power Control. The check engine light has a symbol that looks like an engine, the EML light simply says EML. It usually means that there is a problem with the outputs of the engine electronics, it may or may not be accompanied by the check engine light, which can be referred to as CEL (check engine light), MIL (malfunction indicator light), or perhaps a similar acronym.