Lexmark 4I3 - Manual (Page 258)

The printer displays this message only while Darker or Lighter is
held down. These key functions are valid only after the printer is
ready and the automatic forms thickness adjustment (AFTA)
measurement has been made. It is best to use these keys only
when the printer is printing.
1. Turn the power Off (O).
2. Wait 10 seconds, then turn the power On (|).
3. If the printer displays this status code again, call for service.
A9 FUNCTION NOT AVAILABLE
USE DURING PRINTING
3 PANEL DIAGNOSTICS FAILURE
SEE USER'S GUIDE
31 PANEL COMMUNICATION FAILURE
SEE USER'S GUIDE
312 PANEL COMMUNICATION FAILURE
SEE USER'S GUIDE
314 PANEL COMMUNICATION FAILURE
SEE USER'S GUIDE
316 PANEL COMMUNICATION FAILURE
SEE USER'S GUIDE
32 PANEL COMMUNICATION FAILURE
SEE USER'S GUIDE
B-28 User’s Guide