While shopping, backed into a parking space (don't normally back in), all was fine. Returned to car and red Power Steering light came on immediately, and steering was VERY stiff/unresponsive. No advance warning of a problem, and previous month's Vehicle Health Report gave no indication of a problem. Had to be towed to dealer.

Dealer said they've never seen this before and that several additional codes came up. Dealer said they will have to order an electronic power steering component from Japan since stateside it's on back order. May take 2-3 weeks to get. In retrospect, there was only 1-2 other times where there may have been a related issue, i.e. when attempting to start my car the steering wheel behaved as if locked. Took a few tries before it would finally respond.

Don't know if that was a precursor to yesterday's problem. Only have 15,400 miles on this vehicle and it has otherwise been a gem. This is my first Subaru, and so far, still love it. It came equipped with "Eyesight." Finally, this site indicates an NHTSA item about the EPS being incompatible with Eyesight. Hmmm....

Update from Dec 14, 2018: Dealer found internal fault code C2532; replaced Power Steering Module/ECU assembly. No charge, under warranty. Dealer's senior tech says he's never seen this problem before. Across the nation, 4 were on back order, mine made the 5th. Item came in and replacement done within 2 weeks.