I have this happen to a cmax. The steering racks have an electrical motor rather than a hydraulic one. Mine came up with power steering malfunction, I stopped and started to engine and it then said power steering failure, it was so heavy I could barely turn the wheel, much heavier than trying to turn hydraulic power steering.
I had the rac come out reset the fault codes then it was fine. It had been raining really hard and I think water must have got in somewhere and flashed up a fault.
You should get the fault codes read, you don't want to get stranded with no PAS