| Tammy,
The 27-01 code points to the yellow density sensor not reading correctly.
A common cause of that is that the charge corona is installed incorrectly or is arcing, causing the developer to be drawn out of the unit and into the waste bottle.
Check your yellow corona, and check to make sure that the yellow developer is full. Best bet is to dump the rest and replace with new. Do all of your adjustments and you should be good to go.
Rob |