Can anyone help. I have a 1.8T A4 Cab and the engine management light is on. I had a mobile mechanic look at it and he said it was the lamber sensor on the manifold, he changed this with a new one and the same fault is showing when he plugged it in, aparently there is no reading at all from the sensor. The engine misfires when cold but seems to be OK when warm. Has anyone else had this isuue? Can anyone help?