I have the same problem with mine (the high voltage) but I don't know why.
I took my Throttle Body off to clean it and put it back together and started getting this trouble code too.
I don't worry about it cause the voltage is within specs and the idle and performance are better than ever.
Max voltage when testing the wires with a multimeter or testing with a scan tool should be 4.4volts if I'm not mistaken.
If your getting "voltage to low" that means that you won't get full acceleration or boost from the */c, cause the TPS is not adjusted properly (not sending the right signal to the computer).
I can't exactly remember off the top of my head but I think it is supposed to be turned all the way to the left (counter clock wise).
Loosen the set screws and turn it the opposite way that it is now as far as you can in the other direction.
You may still get the high voltage code but it should be fine unless the car runs like crap.
92 Bonneville SSEi - Stock - Remaining repairs needed due to neglect by previous owner - ABS/Trac, AC.
Mods so far: Maganflow High flow Cat, Rebuilt */C
Future Mods: Interior swap for Leath, High Output Altenator, Crazy system, Climate Control swap & Custom Exhaust/Intake.
98 Dodge Stratus - Wifes Daily Driver
92 Dodge Shadow - My Winter Beater