Isn't that why the manual says to use an extension cord?
You always use an extension cord but it usually plugs into the block heater cord on the outside of the grill. The block heater cord on my 2013 Escape seems too short to get it through the grill to plug into the extension cord. I suppose you could use two extension cords-a short one to get through the grill which would then plug into the longer one that plugs into an outlet, but I don't think that's what the manual is suggesting. It's probably something simple I'm too dumb to grasp at the moment, but in 45 years of using a block heater, I haven't had this problem before.