H4 code can be reset by prog.14 that means to do the following press #.interrupt.C.interrupt zero will gone out in the screen put 14 press print this will reset h4 code.
If your machine is AR-5316, The problem is in the fusing unit try these steps:
STEP1: Press continuously CLEAR then INTERRUPT then ZERO then INTERRUPT
STEP2: The panel display will turn off it means that you are inside the simulation if not repeat again step1.
STEP3.Then type 14 then press the print button
If
these steps doesn't work you must call an authorized serviceman to
check your machine, maybe something is busted on the fusing unit like
thermostat or fusing lamp.