OBD II fault codes:

http://www.peacockandpurvey.co.uk/fa...e_library.html

P0171 System Too Lean (Bank 1)

http://www.vagweb.co.uk/forums/post-2222.html

17536 - Long term fuel trim, entire speed/load range, bank1- system too lean

17705 - Pressure Drop betw. Turbo and Throttle Valve (check D.V.!) / 17705 P1297 Connection turbocharger - throttle valve pressure hose

17956 P1548 Boost Pressure Contr.Valve Open

This looks useful:

http://wiki.ross-tech.com/index.php/...ry:Fault_Codes

e.g. 17705 code - http://wiki.ross-tech.com/index.php/17705/P1297/004759