Intermittent Power Steering Problem

[G30]

Hi there,

Its my first time posting on here so I hope its in the right area of the forum.

My girlfriends Yaris as recently developed a problem with the power steering. Whilst driving, the steering will suddenly become heavy for approximately 30 seconds then return to normal for about the same period of time. This happens over and over again whilst driving and is making the car almost un-drive-able. The model of the car is YARIS HATCHBACK 1.3 VVT-i T3 3dr on a 06 plate.

I had a look on the forums and found a couple of posts regarding the power steering but the problem was different. If anyone as any suggestions of things to check or try, or if anyone as had a similar problem I would appreciate the feedback before I commit to taking it to a garage.

Thanks,

Michael