Hold the reset button... looks something like this (!), It's in the instruction manual and the door jam where the tyre pressures are indicated... The button is in the usual place down with the heated seats etc... (above ash tray) turn key to 2 hold button for 10 seconds this will reset the tyre pressured, for some reason right now if believes the tyre pressue is incorrect and therefore assumes a puncture or problem...

Light comes on normally when fitting new tyres or adjustinng tyre pressure...