Generator issues automatically starts in OFF position

Onan 10kw generator is in off position however it kicks on automatically within 2 minutes after the house batteries switch is turned on. Generator runs for about two minutes and then kicks off and generator panel shows default code. There is no demand on generator for ac, heat or other. House batteries and coach batteries are fully charged. Any thoughts or ideas that could cause this problem of the generator coming on unnecessarily and going into default mode??? Thanks!