Check engine code PO171

I have a 2002 VW Jetta, my check engine lights is on it was put on the diagnostic and it reads code P0171 DCT text system too lean bank 1. Can you tell me what this means and possibly an estimate on cost toget it fixed?

Faulty mass air flow sensor. Clean with mass air flow sensor cleaner. About $10 at auto parts store. If still having issues, as with mine, you will need to buy a new one. I got mine from German Auto Parts. com. Hope this helps! Germanautoparts.com
Franco