Petrol or diesel?? A$ or A4??:
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Ok. My A4 was using a lot more fuel than it should, so I had it plugged in, and got the same reply as you. I changed the temp sensor and the problem was solved. The reason being the car was remaining on choke and putting more fuel in than it could actually burn, which is not only a waste of fuel but will also turn your emissions reading to absolute fly poo!!
Change the sensor mate, then take the car for a very long run to clear out your cat (cause it will be full of crap) and then take it to MOT whilst it is running nice and hot. All Audi's should run at 90 degrees c, but make sure the cat has had a good heat up before the test.
Good luck with it mate.
Cheers.
Scooby.