gti trouble!!!!!!!!!

[wadi]

hi there let me just say what a great site this is!!!!! right down to business, i have a golf gti 2001 y reg 2.0 8v 80,000mls the engine managment light has come on and i have read the fault code which is saying, 16804 catalyst system bank 1 efficiency below threshold, po420-35-10 intermittant, i was using vag com software to read the fault, i cleared the code and the car was ok for 1 week then the light came back on and the same fault code came up, do i need a new cat or a lambda sensor? or is there any common faults on these cars? air leak etc etc?
any help would be great thanks!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!:biglaugh :

[Col]

Sorry and don't mean to overly scaremonger but...

The 2.0 8v on the MK4 is renown for having piston ring problems letting oil blow past them. This fouls both the cat and the lamda sensor.

[wadi]

mmmmmmm thats sounds about right big col it has been using oil now and again but i hav been using 0-40 grade as i get this for free and maybe its too thin for it, whats needed i think is to change the oil and filter using proper vw stuff, add a little piston ring sealer and clean the lambda sensor what do u recon? thanks for your post