Had the same fault on a Kyocera FS-1010 Mono Laser yesterday. This is my fix and the printer is working AOK now.
Called Kyocera and the very helpful person on their Tech Support heldesk confirmed the Error as Paper Misregistration error and pointed me in the direction of the registration sensor.
The registration sensor arm is located just after the MP Tray feed assy under the first metal roller as you work toward the back of the printer.
Firstly check for obvious signs of paper fragments/pages stuck under the developer unit and paper input. If you can see paper stuck remove it and then check functionality of the machine. Small fragments that cannot easily be removed from under the MP feed assy will require consultation of the service manual on how to remove the MP Tray Feed assy...
With the developer and the paper cassette removed, tilt the printer so it is resting on it's rear door and you can view the underside of the printer.
On the underside of the printer, you will see a large white plastic plate screwed into the base of the printer with FIVE silver colour recessed screws. Unscrew these five screws and the base plate should remove from the printer.
Once the plate is removed you will see a circuit board. On what would be the FRONT SIDE (if the printer were on its feet) of the circuit board you will see two optical sensors with movable plastic sensor flags. The one on the RIGHT is the PAPER OUT sensor and flag for the cassette tray and the one immediately to the LEFT of this is the REGISTRATION sensor and flag.
Check the operation of the REGISTRATION sensor flag by moving it slightly with the tip of a small flat blade screwdriver. It should move freely. If it moves OK then clean the optical sensor for the REGISTRATION sensor flag with a cotton bud (QTip) or canned compressed air if possible.
Put the printer back together again and check functionality.
This was the fix for the one I had on the bench this morning. Hope it was of some use to you.