What does the letters PU mean on the eziset950 washing machine?

Hi,
My simpson eziset950 washing machine will not drain. It will fill up, wash but will not drain. It will keep beeping and the letters PU come up. please help.
Also where can i get a free download for the service manual for the eziset 950. The machine is approx 3 years old & has only been used about 15 times (as my old washer died). It was going fine yesterday.
Thanks