Error code F2-37

This is a drum process control error. There is a small patch on the drum that is read by the control sensor every time the drum rotates.
go into SIM mode by pressing the following keys one after the other "P" "*" "C" "*" and then enter 44 and start then 2 and start - this will run the process control gain adjustment. You can also clear the error by running sim 14. If the error continues after both of these then it could mean a bad drum/patch or a bad/dirty sensor. They may need to be replaced. pull the drum unit out and check the condition of the drum.