Multiple Climate Control Issues Plague Audi SQ5

Had nearly identical issues on my 2013 Q5 3.0T last winter. The symptoms match perfectly, climate control malfunctions, frozen washer nozzles, and various sensor errors. The visibility was seriously compromised due to constant windshield fogging. After troubleshooting for a while, the workshop found an electrical issue with the humidity sensor wiring harness. The connection had deteriorated due to constant temperature changes, causing multiple system malfunctions since the humidity sensor feeds data to several control modules. The fix involved replacing the wiring connector and recalibrating the automotive sensor system. Total cost was 95 Euro for parts and labor. Since then, all systems have been working flawlessly. Before suggesting specific fixes, could you share: Current mileage, Any recent work done on climate control, Specific error codes showing up, When the problems first started appearing With this info, I could provide more targeted advice based on my experience with a very similar vehicle.

Thanks for sharing your experience. My SQ5 has 139807 KM and just had its regular service last month. No climate control work was done during that service. The error codes vary but consistently point to the sensor calibration system. The windshield fogging started about 2 weeks ago, with other issues following shortly after. Your solution sounds promising, will have the workshop check the humidity sensor wiring harness specifically. The symptoms matching so closely gives me hope its the same root cause. Definitely beats replacing multiple components when it could be a single connection issue causing all these problems.

Great to hear back and those details help confirm my initial thoughts. The timing of your issues, starting with windshield fogging followed by other malfunctions, matches exactly what I experienced. My SQ5 showed the first symptoms around 135000 KM, very close to your mileage. The humidity sensor malfunction typically cascades into other systems because it provides crucial data to multiple control modules. In my case, the wiring degradation was hidden behind seemingly unrelated issues, which is why checking the harness connection first makes sense. One thing I noticed before the fix, the system would sometimes work normally after the car sat overnight, then fail again once warming up. If you notice this pattern, it further points to the wiring connection being the culprit rather than the sensor itself. Word of caution, make sure your workshop specifically checks the connector housing for moisture ingress. Mine had slight corrosion that needed cleaning before the new connection was made, or the electrical issue would have likely returned. The repair should be similarly straightforward and cost-effective if it turns out to be the same problem. Keep us posted on what they find.

Thanks for the detailed feedback. The overnight behavior you described matches exactly what I'm experiencing, temporary normal operation followed by system failure once the car warms up. This really helps confirm the humidity sensor wiring as the likely culprit. Will have the workshop focus on checking the harness connection and moisture ingress in the connector housing. Good tip about the corrosion check too, definitely worth addressing that to prevent future issues. Really appreciate everyone's input here. Will update the thread once the repair is done. Feeling much more confident about the repair direction now, especially since the symptoms and mileage align so closely with your experience. Should save me from potentially expensive trial-and-error repairs.