car is running low boost and is throwing a p1646

[sseigtp]

I have a 98 gtp has slp headers and exhaust, genV sc, fw cai. it is only running between 2-3psi for boost (checked it with my scan gauge) its also throwing a code p1646.
i checked all the vacuum lines and they all look good.

[sseilmnop]

Sounds like boost bypass valve or the solenoid m. Both mine have gone bad but I've got high miles. Boost bypass had hole in diaphragm, found it with a hand vacuum pump.

[Poil336]

P1646 is a boost control code. like he said, either bad solenoid or bad valve. it'll limit the cars boost because, well... it can't put it under boost. so that's to be expected.