All I did is open the side cover and used my compressor to dust of the belt sensor that's on the side of the machine.make sure that the clear plastic and black sensor has no dust.the machine is back in use and no error code

I've gotten this twice with my machine. I don't know what it actually means but it happens when the drive belt slips off of one or all of the gears. To fix it you will have to remove the left side cover. To remove the cover there are 4 screws: two on the bottom, one just below the royal sovereign logo one the left inside face of the bill output area, and one that's kind of hard to get to. You'll have to remove the top cover that the adjustment screw comes through. I thought I was going to break it trying to pull it off the first time, but it snaps in place, so just don't rip it off and it probably won't break. Once you have that out of the way, you;ll be able to see the screw on the left side. When you get the left side cover off you'll be able to see the belt and that it is out of place. It is easier to just pull the belt back towards it proper place while turning the other gears. Once it's in place you can hit the restart button and it should clear the error code...At least it did for me. Good Luck