Lexmark MX521
A 938.04A Service Engine Electronics Error appears on the printer display.
Power off the printer, wait for a few minutes and power it back on.
Remove the toner cartridge and replace it with a known good cartridge. Observe if the error remains.
Remove all the supplies (toner cartridge and imaging unit) from the printer.
Observe whether the printer posts a 31.xx and not 938.04A error after removing the supplies.
LEGACY ID: SO8891
121.xxA or 621.01A service fuser error message is prompted on the printer display.
Here are steps to troubleshoot a 84x.xx error on a MX321, MX421, MX521, MX522, or MX622 printer.