Concerning the first two digits of the details code in xx12 to xxD0 xx=01: Y xx=02: M xx=03: C xx=04: Bk
Incorrect setting of ATR sensor operation values. ATR sensor trouble or a broken/disconnected wire. The drum unit is not installed properly (the copier cannot detect the drum unit) or there is trouble in the unit.

Replace the SALT sensor (clean it). Replace the drum unit (check its connections).