Idle Control System
WARNING: This page is about a different car, the 2001 Audi S4 and 2001 Audi A4. However, it is still accessible from the selected car via links, so may be relevant.
Idle speed is controlled by ECM in conjunction with Throttle Valve Control Module (TVCM). Idle speed is not adjustable. Idle speed can be checked in diagnostic function 04 - BASIC SETTINGS. Because there is no idle speed control it is important to maintain the integrity of the intake air system.
To test idle control system, see appropriate DTC under DIAGNOSTIC TROUBLE CODE DEFINITIONS in appropriate SELF-DIAGNOSTICS article.