Mine is a 2007 Octavia Classic 1.4 16v Petrol. A bit of history.. The engine warning light came on. the car was really uneven and lost a lot of its power. My initial thoughts was coil pack, plug lead(s), spark plugs. I looked at each plug and number 3 was very black. I obtained through my motor factor a new set of spark plugs and the combined coil/plug connector which were duly fitted. This partially solved the problem. I purchased a OBC scanner and plugged it in which produced VAG Code 17535 long term fuel trim system to rich. I reset the engine light and took the car for a 10 mile run. It was better but still not quite right though the engine light did not come on which could mean that if there is still a problem whatever it is might not produce an error to put the light on.

What else do I need to look at ?

I have been around motors for 40+ years but mainly classics with carbs etc. This is a new area for me and fully realise that electronics, sensors etc are very different.

Any help useful.

I can't find 17535 listed in Ross-Tech's Wki but 17536 (lean fuel trim) is. See below for what it says about the latter code - and also read the additional information on fuel trim listed under Special Notes.

http://wiki.ross-tech.com/wiki/index.php/17536/P1128/004392