I picked up a used 2013 C-Max Energi a couple weeks ago and it ran great for the first four days I owned it (20-30 miles/day). I charged it every night on 120 V. On the fifth day driving home from work a yellow wrench came on while in hybrid mode after depleting the HVB battery. I stopped at a gas station and turned it off. When attempting to turning it back on the yellow wrench was back along with a "stop safely now" message and the car would not start. I had the car towed back to the dealership where the tech pulled up codes P0AA6 and U0554. He cleared the codes and it started back up. The dealer kept it for a week to try and duplicate the issue, but nothing happened so I took it back two days ago and have been driving it 20-30 miles/day with no issues.
Has anyone else had anything like this happen to them? Any idea what the issue could be? I don't want to let my wife drive the car with our kids because I'm not sure if/when it will die again.
Any help/suggestions are much appreciated. Thanks.
Attached are correspondence between the service tech at the dealership and Ford and some pictures of the dashboard when it wouldn't start.
Stop Safely Now.jpg 81.37KB 1 downloads
Yellow Wrench.jpg 79.51KB 1 downloads
Dealer-Ford Communication.pdf 74.91KB 9 downloads
Towing.jpg 110.97KB 0 downloads