The engine management light means the car's computer has logged a fault. A steady light usually means you can drive carefully to a garage; a flashing light means stop as soon as it is safe, because damage may be happening.
The light itself does not tell you the cause. It could be a sensor, a misfire, an emissions part or something loose — the fault code narrows it down.
We plug in and read the codes properly rather than guessing; see how it works on our diagnostics page.
You get the code, what it means in plain English, and a price before anything is replaced.