6214-0003 means even though paper was advanced for a specified dimension, paper sensor 1 did not turn LIGHT. Clean paper sensor 1. Check it on input check, post-exposure advance section, post-exposure advance 1. There paper sensor 1 should be light ( when no paper ) and dark ( when paper detected ) . If have not it - try adjust paper sensor 1 on paper sensor adjustment menu. Can do it manually, or automatically.
If after that will not work check voltages on sensor ( transmitter and receiver ) . Look voltage changes, when sensor closed and not. If sensor not working - replace it. If sensor works, but software doesn't see it then can be bad contacts ( connectors, or broke wire ) , or not working board.