So it will be closed loop lambda control.
I would suggest not driving the car if you can, as you could end up with a knackered catalyser
Thats if the fuelling is wrong.
Go to Halfords and get a gunston colortune, its like a spark plug with a window so you can see the colour of the mixture, or get the emissions tested.
I say this because it could be a failed lambda sensor. Just another possibility.
