Multiple Audi System Failures Point to Control Modules

Having some experience working on VAG cars, I faced a very similar issue with my 2020 Audi A3. The symptoms match exactly what you describe, unusual system failures, check engine light flickering, and entertainment system issues. After connecting an OBD-II scan tool, multiple error codes appeared across different control modules. Initially, the workshop suspected a software issue, but the root cause turned out to be a faulty cable connection to the main control unit affecting the entire BUS system network. The repair involved testing the connectivity of all control module connections and replacing a damaged wiring harness section. Total cost was 155 Euro including diagnostic work and parts. Before suggesting more specific troubleshooting steps, could you share: Current mileage, Whether these issues started suddenly or developed gradually, If any recent work was done on the electrical system, Whether you notice the problems more in specific weather conditions, Engine diagnostics codes if you have access to them This could help determine if your case stems from a similar root cause or if other factors might be at play. The malfunction indicator behavior you describe strongly suggests a communication issue between control modules rather than individual component failures.

My last service was just 2 weeks ago and with 177874 KM on the clock, no issues were found during routine checks. The scan tool revealed no permanent error codes at the time. The warning signals started appearing suddenly after a heavy rain, which makes me think its moisture-related. My service required message keeps popping up despite the recent maintenance. No prior electrical work was done. The OBD-II readings are clean when I check them, yet the malfunction indicator keeps coming on out of nowhere. Think you might be onto something with the wiring harness theory. Will have the workshop check the connections specifically. Thanks for mentioning your experience with the BUS system. This helps narrow down where to look.

Thanks for providing those details. Your description of the issues starting after heavy rain strongly aligns with my A3 experience. When my car showed similar warning light patterns, the malfunction indicator would also appear out of nowhere despite clean OBD-II readings. The timing of your symptoms suggests water intrusion affecting the control module connections. In my case, we discovered that water had seeped through a slightly degraded grommet near the main wiring harness, causing intermittent connection issues in the BUS system network. The clean diagnostic readings between error events are typical for connection problems, as the engine diagnostics only capture active faults. The sporadic nature of your warning lights matches exactly what I experienced before the wiring harness repair. A key indicator that convinced us to check the wiring was how the control module issues increased in damp conditions. Have the workshop inspect: Wiring harness grommets for water ingress, Control module connector seals, Ground connection points for corrosion The repair on my A3 took about 3 hours as they had to trace the exact point of water entry. Afterwards, all unusual system failures and warning light issues completely resolved. If your symptoms match my experience this closely, addressing any water ingress points should solve the sporadic malfunctions affecting your vehicle systems.

I appreciate the detailed insight about the wiring harness and water intrusion possibility. Those failure symptoms do match my situation perfectly, especially how the warning signals appear more frequently in wet conditions. Got an appointment scheduled for tomorrow to have them check the wiring harness grommets and control module connections. Makes total sense about the clean OBD-II readings between events, that was confusing me before. The service required message popping up despite recent maintenance now seems clearly linked to the intermittent connection issues. Will have them pay special attention to those ground points you mentioned. Really hoping its just water ingress through a degraded grommet rather than needing the entire harness replaced. The fact that the malfunction indicator and control module issues started right after that rainstorm seems too coincidental now. Will update once they check the connections and seals. Thanks for helping pinpoint what seems like the likely culprit behind these unusual system failures.