After lowering my 2001 A6 4.2 with H&R coilovers my car was fine.  I had a small incident which resulted in having a headlight replaced.  Once the power was disconnected by the body shop, my car threw a code that the headlights were not adjusted.  The error code displays in the center display.

I took the car to the dealer to have the car 'reset'.  The car wouldn't go into basic settings since it was lowered 1.5 inches with the coilovers.  They told me they would have to contact AOA to get a special 'code' to allow the car to go into 'basic settings'.  After $185 dollars my code was cleared and my headlights were adjusted.

I took the H&R suspension off my 4.2 and replaced it with stock.  As you might have guessed, I had the auto leveling headlight problem again.  After hours of attempting to adjust the lights with the VAG tool, I was unable to get the car to go into 'basic settings' to allow the headlights to read their new level.

I surfed AudiWorld, checked VAG-COM egroup and emailed individuals to determine the fault.  I had one very nice man - Rucklett - help me from Sweden.  He pointed out that the error code I got was from the sensors shorting B+.  This pointed me to the fault at the sensors.

Turns out that the dealer had adjusted the sensors to read the new lowered suspension.  After I bent the sensor brackets back into place, I was able to read -08 Measuring blocks to be sure I had the correct voltage coming out of the sensors.  Once I had them back to their 'original' position, I was easily able to go into -04 Basic Settings and adjust the headlamps.

I hope this helps others!