Audi Repair: Audi A3 Throttle fault/feature ?, high idling, audi a3

Question
I have an Audi A3 1.6 petrol, year 2002.
The car takes an emission test and the test condition for high idling is 2000rpm. The test cannot be carried out because the car cannot maintain a stable 2000rpm i.e. it hits 2000rpm and automatically drops back to much lower revs position after a second or two. Is this a fault or a feature ? The guy who tested the car wasn;t 100% sure. If it is a fault, is it a well known one and what is the diagnosis ? BTW: the engine fault light has been on for the past year, repeated attempt to clear the problem have failed.

Answer
If the engine light has been on, then it probably needs an O2 sensor which will mean for an emission check the engine runs too rich...  If you get the fault codes read out, you can see if this has something to do with the mixture, and you can take care of that.  With reference to changing the idle, the idle is controlled through an idle control module and therefore cannot be increased.  If the engine has to be revved to 2000 rpm for the test, someone has to increase the throttle position slightly, either by putting a (steady) foot on the accelerator or under the hood.  Let me know,  Jan