PAS Pump repaired but fault light still on

Hi,

had the power steering pump replaced but the yellow light showing a fault is still on.  I bought a second hand pump/control unit which had been tested and which had come from another roomster that had only done 10,000 miles.  Once replaced with this unit the power steering has worked fine.  The Garage that fitted it was a Skoda specialists but not an authorised dealer.   The engineer said their was still a fault in the unit but the place I bought the part from said it had been tested and was in good working order (which it is!)

Before I got the Skoda specialist to fit it I had inquired at a local small Volkswagen dealer and the engineer there said that sometimes second hand parts won't accept the codes?   So I'm wondering if that is the problem........  I took it to the specialist in case I had any problems and thought they might be equipped to sort it out....so not sure now....     The skoda specialist also said that every second hand pump they have fitted has never worked (or has remained with a fault).    

So, my steering all works but need to find a way of clearing the fault indicator light - 

 (would an authorised dealer be able to get the pump control unit to accept the codes...if this makes any sense?)

Any ideas???  

Thanks

John