I have a 1993 Audi 100 CS Quattro with a yellow warning symbol frequently alarming from the auto-check system (appearing every 30-60 seconds with loud beeps).

It indicates that I have a defective head/tail light but all of my lights are working just fine. This has been a problem for a few weeks now and I would like to switch off this warning symbol, as it is fairly annoying. The user manual says, "the yellow symbols in the display can be 'switched off' by pressing the check button" (located between the coolant temp gauge and tachometer). However, when I tried doing this while driving, the system beeped twice and a different symbol appeared ("MPH" inside a circle), followed by the usual symbol indicating a defective head/tail light. The problem remains. Do you know how I can get rid of this warning when everything is actually functioning properly (all except my auto-check system that is)?