A U2 is related to a memory failure. May be a bad memory chip or main board. BUT, before we get drastic and move in that direction there are a couple of other things that I have seen cause that.
So, first I have seen the chip on the back of the drum cartridge cause that problem. You can try removing the drum cartridge and powering on the machine without that installed. See if it just comes up with a J2 code then. Or even a CH code. If the code changes you may simply have a failed drum cartridge.
Sometimes memory corruption can occur and you can clear it using this procedure..Performing a Fault Reset 14 will reset your WorkCentre and will help to clear error codes.
- Find the pink Clear button on the Control Panel of the WorkCentre.
- Find the button below the word Auto.
- Press these buttons in the following sequence: [Clear], [Auto], [Clear], [Auto]
All of the lights on the Control Panel should go out and the LED
Display should go blank. If the lights do not go out, then repeat step
3 until they do. It may be necessary to increase or decrease the pace
of the [Clear], [Auto], [Clear], [Auto] sequence.
- Press the [10's] key one time and the [1's] key four times to enter '14' in the LED Display, as if you were to make 14 copies.
- Press the green [Start] button.
- Press the pink [Clear] button two times.
- The WorkCentre should now warm up and come to ready.
- If the above steps do not clear the error code, repeat steps 3 to 6 a second time.