As I pulled off the A1 last night the car started mis-firing and the engine management light came on... I managed to get home (4 miles).. Called Audi today and they told me to leave the car with them. They called me to say that the 4th coil needed replacing... I have heard of "Coils" as a friend of mine had a few on his Golf GTI in the past, but what are they ? Seems strange on this car since the service was only carried out a few days ago. ? ?