My C3 started having this problem on Monday. Drove to Sheffield from Leeds with no problem, parked up, popped into a shop and BAM, could hardly turn the wheel to leave the car park.The AA had to come and, after about half an hour of unsuccessful attempts at diagnosing the problem, located it to the ECU and reset my ECU, causing me to lose my radio code, but getting me back home.
The AA recommended immediate garage attention, but the garage could not find a problem. The next day it happened again, this time on my driveway. I turned the engine off, went inside to ring the garage, and when I went back out to take the car to them, it was working again! I still took the car, but again they found no fault.
Today this has happened for the third day in a row, so I tried turning the ignition (NOT the whole engine) on and off three times and VOILA, i felt the power steering come "free" right in my hands!
If this saves me money on a new ECU, great, however I do have concerns about other people saying their steering locked up mid-drive. That sounds very dangerous to me.
sheree, December 2012