Epson AcuLaser C9100 Reference Manual page 314

Writing ROM P
The printer is writing data into the ROM module in the ROM slot
P.
Wrong Photoconductor
An inappropriate photoconductor unit is installed. Install only
the photoconductor unit listed in "Consumable products" on
page 25.
See "Photoconductor Unit" on page 231 for instructions on
replacing the photoconductor unit.
Wrong Toner uuuu
An inappropriate toner cartridge is installed. Install only the toner
cartridge listed in "Consumable products" on page 25.
See "Replacing a toner cartridge" on page 227 for instructions on
replacing the photoconductor unit. (The letters C, M, Y, or K
appear in place of uuuu and indicate the colors Cyan, Magenta,
Yellow, and Black respectively.)
wwww Open
The specified cover (wwww) does not close securely. To clear this
error, close the indicated cover. wwww indicates the either cover
name; cover A (front cover), B (left hand cover), D (Duplex Unit
cover), or E (tray module cover).
314
Troubleshooting