Why does the engine management light stay on in my Ford Mondeo when the car is running OK, it happened a few weeks ago and had it put on diagnostic machine and light went out.
The light comes on because the cars computer has detected a problem. Turning the light out does not repair the problem!! You need to plug it in to the diagnostics again and tell us what fault codes have been stored.
Include more detail such as the cars year, engine, fuel type etc.