I found this instructions. Try them and post if it works.
Reset Waste Ink Code
1) Enter SERVICE MODE by pressing sequentially Menu Copy Scan Copy Copy or Menu Copy Copy Copy Scan (on some models)
2) Select TEST MODE.
3) Press '+' 8 times till 'Select [8]' PRINTER TEST in TEST MODE.
4) Select 3. [EEPROM CLEAR].
5) Select 0. [INK COUNT].
6) Press the [OK] key.
7) Press the [Stop/Reset] key (returning to the state of 3)), and then press the [ON/OFF] key.
8) Done
ivanick, August 2007