I have fitted a friends tuning box on my 1.6 Zetec Focus TDCI (59 reg). The Tuning box is a Rover Ron taken off a Mondeo Zetec S TDCI. It works fine on the Mondeo. For some reason, when I plug it onto mine, an Engine Malfuntion Warning Signal appears and it puts the car into limp mode. As soon as I take the tuning box off, the warning light clears and the car goes back to normal. Does anyone know whether this has something to do with this particular tuning box or will any tuning box fail to work with this car?