'91 200q fault code 4442

[C1J1Miller@aol.com]

My '91 200qt 20v has seemed down on power for a while; boost also doesn't
seem there, and has gotten less with time.  The guage in the trip computer
says a max of 1.7 bar, with average max at 1.6 bar.  I know, that guage is
notoriously inaccurate.  Can't find any vacuum leaks but I didn't spend a lot
of time looking.

So, using the jumper/LED procedure, I ran the fault codes (engine off, key
on), and got code 4442, then code 2221, end of codes.  Code 2221 I ignored,
as the engine was not running.

Mr. Bentley says 4442 means the following:

Wastegate frequency valve (N 75) 
*Short circuit to positive   *Open circuit or short to ground
:Problem:  
Short circuit to positive in (N 75) and/or in wiring connection between (N
75) and terminal 23 of (J220).   
Short circuit to ground in (N 75) or in wiring between (N75) and terminal 23
of (J220).
:Symptom:
Boost pressure too high.
Boost pressure too low.
Severe misfiring during full throttle.
:Repair:
Check (N 75) Repair Group 24.

I'm going to check the waste gate frequency valve resistance et at re: Mr.
Bentley's procedures.  Anyone BTDT?  Does this fault sound familiar, and what
was the solution?

Last bit:  The error code section keeps mentioning VAG 1551.  Seems like a
great thing to have.  Anyone bought or priced this?  Is it worth looking
into?  Sources?

Thanks, and sorry for the long post.
Chris Miller
c1j1miller@aol.com
Windham, NH