I just went to Advance and had them hook up their OBDII scanner to my 2000 Disco II, i got back a code P0455 , an emission control system leak . I was wondering if any of you guys had a good starting point for me, to figure out what is wrong? Thanks

 

This code is actually for "Gross Leaks", could be a really bad gas cap to a vapor leak from one of many vapor lines from the canister to the fuel tank.

 

I'd bet my house its a Gas cap failure..

They can be had for about $30 @ the dealer.
Install it yourself and save about 3 hours worth of diag testing. [:'(]

 

Yeah,check your gas cap, for some reason after time the cap fitting in the filler neck will become to tight, causing the cap to "click" before it is fully seated/sealed. a new cap will remedy this. check the fitting does it close freely or with alot of resistance?