When started my truck, dash board shown “Steering Assist Fault Service Required”, and "Collision Warning Not Available ". The steering wheel locked and couldn’t turn either left or right. Brought my vehicle to dealer and they’ve told me there’s no problem with it. In order to diagnose the problem, the message must shown. The problem is it doesn’t show the message every time when I start the truck.
You have a problem with your electric assist power steering. Hopefully still under warranty. Next time this happens, have it towed to the dealer so they can see the message. Good thing is… it will likely get worse and it likely won’t fix itself.
I’d suggest you have your battery tested. It may be on the way out and electric steering is sensitive to that.