Hi Scotty, I have a 2008 Touareg base model with a 4.2 V8. Auto transmission with AWD. it left me stranded in limp-mode. Checking the codes I found four of them. P0413 ( Secondary air injection system (SAIS) valve switch A open circuit) P0416 (Secondary air injection System Valve B circuit open) the dreaded P129B (refer to vehicle service manual) and lastly a P2294 (Fuel pressure regulator 2 Control circuit fault code). 

For the SAIS I checked/ stroked the valve switches and the Air injection pump all are fine and within operating parameters. I changed out the fuel pressure regulator on bank one and two. Bank one seems to work fine bank two still displays the fault code.  now I still stuck as to were to go to next. Any suggestions? 

TIA