Serial number please.
It is for your Auxiliary control roller on the right joystick.
You will have to go into the monitor's service mode. Key on, press and hold the Menu button for 5 seconds. It should beep and then read Service Mode. Scroll to codes. Press select. Scroll to delete codes. Press select to delete. Then use back button to get out of codes and then scroll (next button) to diagnostics. In diagnostics look for Right Joystick. Press select. Look at Roller Channel 1 and Roller Channel 2. Record your readings as they are, then roll the right joystick aux roller all the way forward and record your readings, then all the way rearward and record your readings. Post here. If the code comes back while doing this it is most likely a bad roller, which would be the handle assembly at roughly $340.