Used generators come with a DOA warranty. "Dead On Arrival" warranty makes sure that unit will work when it comes. It was tested and checked before it leaves so that you know it will arrive and work as you expect. Because it is a used machine that is where the warranty stops. You have 90 days after purchase to install and make sure unit is working correctly. If unit is not installed correctly or gas connections are not done to spec this will make unit not work correctly. Because we are not doing the install we can not do a longer warranty period. All units that we install will come with a 1 year warranty.