A8 Climate & Visibility Systems: Multiple Failures Alert

Having encountered something similar on my 2021 A7 Hybrid, I have some experience with climate control malfunctions. The symptoms you describe match what I faced, multiple system failures pointing to a sensor calibration problem. The root cause in my case was a damaged wiring harness connector near the windshield sensor array. The workshop found that moisture had corroded the main plug connection, triggering dashboard warnings and causing those exact issues, AC malfunction, washer system problems, and mirror heating failure. The fix involved replacing the corroded connector and recalibrating the sensor system. Total repair cost was 95 Euro, including diagnostic work. Since then, all climate and visibility functions have worked perfectly. To provide more specific guidance, could you share: Any dashboard warning lights currently showing? When did these issues first appear? Have you noticed any windshield fogging issues? Did the problems start gradually or all at once? This information would help determine if your A8 is experiencing the same connector issue I had with my A7.

Thanks for the detailed reply. After 199698 KM the dashboard warning lights started appearing last week, all systems failing at once. The humidity sensor seems particularly problematic, with constant windshield fogging even in dry weather. The car had its last service 3 months ago with no issues reported then. No warning lights showed before this, but now multiple dashboard warnings appear related to the climate control system. The error codes point to sensor communication failures. Based on your experience with the connector issue, this sounds like it could be the same problem, especially since the timing matches, everything failed simultaneously just like in your case. The workshop availability is limited right now, would you recommend this as an urgent repair? The constant fogging is becoming a safety concern.

Thanks for those extra details. From my experience with the same issues on my A7, I would classify this as urgent given the safety implications of poor visibility from windshield fogging. The simultaneous failure pattern and the high mileage match exactly what happened with my vehicle. The humidity sensor malfunction combined with the climate control issues definitely suggests a similar wiring connector problem. The constant fogging indicates the system cant properly regulate the cabin environment since the sensors arent communicating correctly. While my vehicle had lower mileage when the issue occurred, the repair process should be identical. The immediacy of all systems failing points strongly to the connector corrosion I experienced rather than individual component failures. Given your cars mileage, I would also recommend having them check the entire sensor calibration system while doing the repair. In my case, they found that recalibrating all climate control sensors after fixing the connector helped prevent future issues. Until you can get it to a workshop, try these temporary measures that helped me: Run the ventilation at maximum to reduce fogging, Use manual climate settings instead of auto, Clean the windshield thoroughly inside and out to minimize moisture buildup The repair itself should still be relatively straightforward, likely costing similar to my 95 Euro fix, though prices may vary.

In response to your helpful input, I definitely agree this needs urgent attention. Your description of the wiring harness issue matches my symptoms perfectly, and the safety concern with visibility is becoming critical. The electrical issue affecting multiple systems makes even more sense now that you've explained the connector corrosion problem. I'll try your suggested temporary fixes with the ventilation and manual climate settings until I can get a workshop appointment. I called another repair shop and managed to get scheduled for next week. They estimated around 120 Euro for diagnostics and repair, including the sensor calibration you mentioned. The constant dashboard warnings and failing humidity sensor are concerning enough that I don't want to risk waiting longer. I'll implement your tips about maximizing ventilation and cleaning the windshield thoroughly in the meantime. Really appreciate you sharing your experience, it's helped narrow down the likely cause and given me a clear path forward for fixing these automotive sensor problems.