Hi I found this on the HP website:
http://h30499.www3.hp.com/t5/Color/4650n-error-49-5001-will-not-clear/td-p/3442896?notmigrated#.Vd3lWJctJZQ
from what i read it could be a firmware issue or a maintenance issue, there are a few thing the people listed here that might fix this error by holding down a button and doing other steps, this might help, most of the time though printer issues are caused by wear and tear or it needing updates