O2 sensor and low boost

[Mayszak, David A]

I'm an "old" newbie in that I've been reading the postings for about a year,
but this is my first posting.  I've had my 200 20v for about 10 months now.
It has always run well, started quickly and idled very consitantly and never
stalled.  However, I've never been able to get it to boost higher than 1.2
bar.  The Multi function temp sensor was faulty and has been replaced, but
did not improve the boost.  The wastegate bypass valve is new along with the
frequency valve.  I've also relaced the hose which runs from the WGFV along
the manifold to the back of the engine and have checked the "Michellin man"
hose.  The plugs are fine and correct. I'm now suspecting the O2 sensor.  My
questions are; can a faulty O2 sensor result in retarded boost???  What, if
any other symptoms may a faulty O2 sensor cause?? If the sensor is bad and
disconnected, would I see a difference in the car's performance??  and the
present O2 sensor has three leads to it, is this a generic sensor or an OEM
replacement???

Any help would be greatly appreciated.

Dave