If the fault was mechanical then it will be the owner’s physical and financial responsibility to pay for the repairs. The owner will as well be responsible to collect the RV from the repair shop in case the renter is unable to do so.
If the fault was caused by the renter then the renter will be responsible for covering the RV owner’s costs to retrieve the vehicle (in case the renter is unable to drive it back) as well as the cost of repairs.