i have a faulty mechatronic

should i buy a new one or a used one from scrap dealer.?

Depends how much less the used one costs. 

 

If it were much much less than a new unit, then I might be prepared to take a gamble.......if I could find one from a car that has only recently been scrapped. I wouldn't want one that has been lying around for a year or two. 

price is about 50% of new unit(or less)

say if i get a unit from 2008 model, will it work fine on my 2006 model?

Take a look at the two links below this may be an option for you.

 

http://www.ecutesting.com/dsg_gearbox_ecu_removal_instru.html

 

http://www.ecutesting.com/vw_and_audi_dsg_gearbox_ecu.html

 

You could have you mechatronic unit repaired and have a two year warranty for the price of a second hand unit.

brother they are in uk n m in india.

if u add up the taxes n make a estimate bill it will be more than a new unit.

Maybe there is a place in india that repairs mechatronic units. Try google. I wouldn't be overly confident in a second hand unit. You could buy it and it also could be faulty or go faulty quite soon afterwards and you would be in the same position as you are now.

One thing from my earlier post is now you know how to remove the mechatronic unit safely. Don't forget to factor in a DSG oil change as you have to drain the oil.

To be honest, 50% less than a new unit would not be cheap enough for me to take the gamble. I'd go for a new unit.

 

But to answer your question, I don't see why a 2008 unit would not fit a 2006 gearbox. The gearboxes should be the same.