[s-cars] Lambda replacement?

[Theuns Pelser]

Ok I have been warned that this is not the best place to post my A3 Audi 18T(AGU) Q's.... but  have to disagree based on what I've already learned here.(still open to suggestions of lists to try)
 
I feel I need to replace the Lambda on my A3 since it has covered 160k  km.(99419miles) and it doesn't look like it has ever been replaced.
 
So can I do this myself without Vag-Com or remapping? and what type should 
I get? or should I get the OEM?
 
Appreciated
Theuns
SAfrica
http://www.audiclubsa.org.za/