843.99 on the X73

[Iowatech]

For what it is worth, I found out today that this error code is probably is due to dirty sensors in the document feeder.

[blackcat4866]

Yes. If you search you can find a Lex bulletin about it. Essentially, there is a sensor in the DF top cover that looks a little like a thermostat. It's easy to miss since it's dark gray, in a dark gray housing. All I had to do was clean the surface. =^..^=