1995 Thunderbird SC code 326

Hey guys I have a 1995 Thunderbird SC that I am working on. While doing a key on engine running test I got a code 326. The book I have says the the puessure feedback sensor or the pressure transducer voltage is lowere than expected. Could someone fill me in of what this means and what I need to do to fix it?

Thanks alot
Andy

andy i ran into a code 332 a week or two ago and had a vacumn leak at my pfe valve. this valve is located on rear drivers side of engine and casn be seen from the bottom looking up besied the trans. it has a pink and a blue vacumn tube connected to it. u could check the conection of the wires also hooked to it for corrosion. they go to the computer and is one end of this codes curcuit. hope this helps ronnie