your belt home sensor is getting dirty from dumping toner from the direct pipe assy being clogged due to clumps of toner from humidity. clean out or replace whole waste recycle system. this is an ongoing issues with these style machines from the 700 to the versants.
In this case seems to be the IBT is so used. Don't worry, the print mode will become disabled if 3 times error appear, but resetting the NVM it will be enabled again.