Twin turbo Bob

Hi am a Newbie just purchased a 2004 S type 2.7 after driving several hundred miles trouble free till on a recent motorway had a small amber light intermittently flashing and a message restricted performance the car is running fine performing as usual accelerates really well on returning home plugged the OBD in no code showing took it out today for a run running really well same message again am a bit stumped can understand if it was in limp mode any help would be most appreciated