940.00 Serial communication failure between the controller board and engine board error
A 940.00 error occurs when the black toner cartridge encounters a hard stop. Serial communication failure between the controller board and engine board
Issue description
A 940.00 error occurs when the black toner cartridge encounters a hard stop.
Solution
Update the printer firmware to the latest version or at least an xxxx. 230.210 firmware level. See the instructions in Firmware Update Instructions.
Since the issue is triggered when the black toner cartridge encounters a hard stop, an empty black toner cartridge meets that condition. Therefore, there is a need to replace the black toner cartridges after upgrading the firmware.
If the issue persists, then contact customer support.