Low mpg

[neil]

Lately my 2003 leon cupra has only been getting 18-19mpg , used to 33-35mpg. There is no smell of petrol anywhere and the only fault code thrown up is p0420 , is this related ??
cheers , neil.

 

[turbo009]

When was the last time you serviced it? You changed your plugs recently ?

 

[neil]

a service is due , cant remember when the plugs where last changed .

 

[turbo009]

Naughty,can't remember,sounds like it does need a full service mate Deffo get your plugs changed tho asp