This specific error is not a simple paper jam or an out-of-ink warning. It is a hardware-level stoppage related to the machine’s critical paper transport and registration system. In plain terms, indicates a Timing Mismatch: Paper Position Sensor (PF Register Sensor) abnormality.
Once you have cleared the error, you want it to stay away. Implement these three maintenance habits: riso error a16-525
: If the drum isn't stopping at the exact right angle, the sensor may be looking at the metal body instead of the velvet strip. In Test Mode, Simulation 941 (Position-A adjustment) or Simulation 942 can be used to tweak the drum angle. This specific error is not a simple paper
: Ensure there are no paper jams or obstructions that could be causing the error. riso error a16-525