My Danby DDR657EE shows P1 periodically also. So, I called Danby.
Danby's Consumer Help Line (1-800-263-2629) is always busy. So, I called their General number: 419-425-8627. The receptionist transferred my call to their Service dept. My call was answered in 2 minutes.
The Service Rep. described the following code for my dehumidifier model (DDR657EE):
P1 = Defrosting: the unit will go into Defrost mode periodically to ensure that the parts are working at the right operating temperature. It should be in Defrost (P1) mode for only a brief period of time. If the unit is in Defrost (P1) mode continuously for a couple of hours (or more), then you should call Danby Service for further assistance.
He had no documentation of a P2 code for my model.
He also described other General Codes (applicable to most Danby Dehumidifier/Humidifier models):
E1 = Not enough water
E2 = Not draining
E3 = Water temperature too cool
E4 = Overflow Switch activated
E6 / E7 = Problem with Temperature Sensor
So, if you see P1 periodically (for brief periods), then it would be normal.
Also, here is a link to Danby's FAQ page for Dehumidifiers (which answers some common questions):
I hope that helps.