(G) Steering - Intermittent fault

I know that it must have been done a million times but my daughter's Punto 1.2 16v ELX is playing up. The power steering packed up just before Christmas and then miraculously cured itself after a day or so. I read through lots and lots of stuff and the concensus was that the steeing unit was on its way out and so the weekend before last I put a repalcement on; a used unit but with a 6 month guarantee from a very reputable Fiat used spares.

Last night the steering failed again; the symptoms are as before, steering goes heavy and the warning light comes on. This morning the steering is fine again. I concluded initially that the replacement unit was faulty and was all set to take advatage of the guarantee, but now I am not so sure.

I wonder therefore if there could be another reason, other than a faulty unit, for the intermittent nature of the fault, such as a duff switch, relay or cable. Does anyone out there have any ideas? If so, I would love to hear them!

Many thanks

go get it checked and diagnositc because the error will be logged and get it inspected because u do not really want it to go while driving and take advantage of the guarantee use it to ur advantage especially if it needs replacing