Lexmark X850
Intermittent 900 firmware error appears on the printer and scanner is too hot at some point.
Turn off the printer and power it back on after one minute.
Check the printer if the error message still appears.
Check the surface of the scanner and verify if becomes too hot.
Does a 900 error message appear on your printer? Check out the following steps to troubleshoot the problem.
'945' Service Imaging Error or 'Service Image Processing Unit Interrupt Handler Delayed Crash 109' on a X64x, X85x, and X77x Series MFP or Lexmark 4600 Scanner-Equipped Printer