Section 14 (Automatic A/C-Heater Systems): Self-Diagnostics: Notes

WARNING: This page is about a different car, the 2001 Audi S4, 2001 Audi A4, 2000 Audi S4, and 2000 Audi A4. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Scan Tool (VAG 1551 or VAG1552) must be used to make full use of the system's self-diagnostic capabilities.

A/C-heater control panel receives input information from various electrical and electronic sensors. This information is processed by control panel according to specified values. Corresponding output signals are provided that control electrical actuators. Control panel is controlled by an internal microprocessor with On-Board Diagnostic (OBD) capability. If faults are detected, Diagnostic Trouble Codes (DTCs) are stored in DTC memory. Stored DTCs are identified using either VAG1551 or 1552 scan tool.

If a fault exists for a certain time, it is stored as a STATIC FAULT. If a static fault is no longer present, it is stored as a SPORADIC FAULT and the reference "SP" appears on the upper right of scan tool display or print out. Before replacing a component suspected of malfunctioning, check all related wiring, connections, harness connectors and ground connections using wiring diagram. Output Diagnostic Test Mode (DTM), Basic Setting, A/C control panel identification and coding functions are also possible.