Audi Repair: MIL 2000 A^6 Quattro, degree temps, humid air

Question
My MIL lamp goes on every year during the Nov to Apr time frame when the weather and humidity fluctuates quite a lot.  I can predict when the light will go on by the weather outside.  (For example we recently had a spate of warm humid air,70degree, after 40 degree temps during the day and mid 30 temps at night.  It will go out when the weather gets cold and drys out.  This has been going on since I purchased the vehicle new.  The dealer never found a code and reset the light.  In Jan 2006 when I had it checked there was (the MIL had been lit but had gone out) there was no code.  Two weeks ago there was an EVAP .002 of an inch code in memory.  The light had been on but had gone out when I took it in for a check up and oil change.  The only reason I am interested is that the car has to go through emissions every 2 years in Feb.  I have only passed once.
Thanks

Answer
hi
If the MIL light comes on , fault is stored in ECM.
When system pass it own selftest MiL goes out but fault stays in ECM and is only changed to sporadic.
So, to help you with better  I need P code #.
Every fault in ECM has letter P and 4 numbers
That's what I need>>