Check Steering Light on Renault Megane Dynamique???

Hi there,
The 'Check Steering' light is up on the little screen. Took it to a mechanic with a diagnostic computer and it showed everything as being fine. Same thing happened with the RAC. Both said to take it to the main dealer, but they cost an arm and a leg just to look at it. Does anyone have any ideas please?
Thanking you.