Quick question for my inlaws ! They have a ford focus diesel that has suddenly developed a fault, from what they told me it has a fault causing it to stall but not when idol or waiting in traffic it's when they are turning I.e corners roundabouts, on most trips it will do it 2-3 times, they mentioned the panel where the mileage is says power steering fault, they are thinking of part exchanging car because they don't want to waste money repairing it, do anyone know if it's a common fault easy fix or exspensive sounding fix