I have a 2000 Octavia 2.0slxi and all was fine until there was a rattling from underneath that I couldn't trace as it only rattled over potholes etc, it has now stopped rattling but now the engine light is on and the car is not doing very well on fuel now. Doing 25mpg as opposed to 35. Other things I have noticed are a nasty eggy smell when ticking over and a couple of black stains on the drive from startup.

I am thinking the cat may have gone but without diagnostics am looking for some advice to narrow the search.

Thanks for any ideas

Simon

Whoops, this should be in the Octavia 1 section. Mods feel free to move please

Edited 30 May, 201016 yr by Bouncerbeater

I'm pretty sure that a rotten-egg smell is indicative of a knackered CAT. Not sure how much they are on Octys, but the one on my 2.0 Primera was only about £80 so perhaps it won't be too expensive to sort either.

You'll need to get the codes read as to why the light is on, at least it is on, so there'll be something there to read. A friend had very poor fuel consumption on his Golf 2.0 (I beleive that it is the same AQY engine), without any lights on and no codes to be read. I guessed at a faulty pre-cat lambda probe, which when it was replaced returned the fuel consumption back to its usual level.