P000 is an error (AWOS)

I talked with a METAR expert at the NWS today about the P000 (three
zeros) group. I've long been bothered by the fact that many AWOS's
include the group all the time; moreover, according to the specs,
there should never be THREE zeros.

A P0000 (four zeros) indicates that there has been an undeterminable
amount of precip. If there has been NO precip, then the group should
not be included.

The guy assured me that AWOS's are in error. ASOS's do not have this
problem. He also said it's the FAA's fault, since they govern AWOS's.
He says they have complained loudly about the problem, but the FAA has
yet to fix it.