I have a 53 plate 2.0 TDI A3. The emission control system light has just decided to make an appearance on my way home and I have to be honest im dreading taking it to the garage. Can anyone give me an idea of what the problem is likely to be or what its likely to cost me best and worst case. Also am I safe to carry on driving it until I can get the several billion pouds together it costs every time my car throws a strop!

If it helps to identify the problem at all I had just filled up
with fuel when the light came on and i did let it run rather a little below the red line.

Any help greatly appreciated.