This is a diesel (1.8 Tdci). I had a quick look and could not see any damage although it is quite tight in there to see a great deal!
The car is under warranty so obviously I should take it in, however it seems that other people who have had the "Engine Malfunction" warning with no fault codes, have not had much luck getting it sorted out. The car apparently had a full service when I bought it 4 months - I will have a look at the filter if I get a chance before taking it in (just to be curious). The dealer seems fairly honest as I had a couple of new tyres and when fitting them they noted that part of the suspension would need replacing within the next year or so - I asked them if they would do it there and then under warranty and they did.
I suppose I am slightly worried that if/when the warning comes back it will have an effect on something. Most people say the car goes into limp mode when you get this - not sure why mine allowed me to carry on as normal...