Hey, I just picked up a 2001 TT 180 Quattro last week. It has a forge diverter, GIAC chip and 225 exhaust. It has a VDO boost gauge but the boost only goes to 5 psi then seems to taper to 4. It has a CEL but seems to boost fine. Any ideas on what could be wrong? Thanks

 

Something has caused it to go into limp mode. Scan the codes and see what threw the cel and fix it and the boost will return

 

there is a difference between boosting at 5psi and 16psi which is what your probably around with the chip...

have you ever boosted to 16 or so? if not, maybe thats why you think it seems to boost find and your in for a little treat when you get the cel fixed and out of limp mode