VW Taos HVAC Failure Linked to Air Sensors

Recently dealt with a similar HVAC sensor issue in my 2019 VW Tiguan. The symptoms started exactly the same, auto recirculation became erratic before the blower failed completely. The BMW AUC sensor and related air quality sensor components are actually quite similar across VW models. A diagnostic revealed the main issue was corroded wiring connections at the AUC sensor plug, likely from moisture buildup in that area. The sensor itself was functioning, but the signal wasnt reaching the control module properly. The fix required cleaning the connector pins and replacing the wiring harness section connected to the sensor. While not a complex repair, accessing the components behind the dash made it a time-consuming job. Since the air quality sensor is part of the safety system controlling cabin air, its important to get it fixed properly. Worth checking the basic fuses first, but based on the progression of symptoms with the auto recirculation, this sounds like the same sensor fault issue. Would recommend having a shop do a proper diagnostic rather than parts swapping, as pinpointing the exact connection problem saves time and parts costs.

Thanks for sharing that experience with the Tiguan HVAC sensor issue. I had been worried about a costly sensor replacement, but your post gives me hope its just a wiring problem. Would you mind sharing what the total repair cost was? Also curious if youve had any other air conditioning sensor problems since getting it fixed.

Thanks for asking about the follow-up. Taking my Tiguan to the mechanic turned out to be the right choice. The odor sensor fault was exactly what they found, a damaged wire connection at the AUC sensor plug, just as suspected. The repair came to 95€ total, which covered cleaning and fixing the connection. The auto recirculation and HVAC sensor system has worked flawlessly since the repair. The air conditioning sensor network is now functioning properly, with no issues over the past few months. The mechanic explained that moisture-related connection problems with the BMW AUC type sensors are fairly common, but once properly fixed, they typically stay resolved. Considering the initial symptoms you described match my experience perfectly, you might be looking at a similar straightforward fix. The key is having a proper diagnostic done to confirm its just the wiring rather than a complete sensor replacement.

I finally took my Taos to the dealer after reading about your experience. You were spot on, it turned out to be a corroded connection at the AUC sensor, very similar to your situation. The auto recirculation system had been acting up due to poor signal transmission from the cabin air sensor. The repair was straightforward and cost 120€, which included cleaning the connections and replacing a small section of wiring. The technician showed me the corrosion buildup they found, explaining how moisture had gotten trapped in that area. The blower and all HVAC functions are working perfectly now. The odor sensor and auto recirculation features are back to normal. Really glad I didnt jump to replacing the entire sensor unit. Thanks for sharing your experience, it helped me approach the repair with more confidence and knowledge about what to expect.