i would check your seat switch and seat belt harness and switches,
sounds like the operator presence circuit is not working, this disables the trucks travel and hydraulics when it is open.
it would normally show an operator symbol on the display or some sort of symbol showing the operator not being on the seat. Not necessairily an error code.
This is ONLY to be used to report flooding, spam, advertising and problematic (harassing, abusive or crude) posts.