What was the sub code on that E240?
Do you have any accessories connected, finisher, paper deck.
Check and reseat the bootrom and Dimms as well.
Last, DC controller.
Here is more detail info if you haven't check.
E240 ?
Error in communication of controller
Error in communication data
There is no response when 3 sec passed since the main controller had sent the pickup request to DC controller during printing.
There is no response when 4 sec passed since the main controller had sent the request for image output to DC controller during printing.
Check connector, check connection of sub PCB in the controller box, check / replace DC controller PCB / main controller PCB