I recently had this problem on my 01 3.5 74000 miles.

After having the dealer run diagnostics, he told me that there was a computer update for this issue where the computer reads the sensors wrong and that it is actually working correctly.

Also, he told me that there is a TSB on this issue that tells them to change one of the valves and the pump. I was quoted $800 for parts and labor. Kind of expensive for something that doesn't effect the drivability of the car.

One question however:

Is this pump the vacuum cleaner noise that I hear when I Cold Start the vehicle?

Would that noise indicate that it actually is working?