VW Taos Heat Issues Linked to Faulty Solar Sensor

As someone with moderate car repair experience, I encountered a very similar issue with my 2019 VW Tiguan. The heating system started acting erratically, and the daylight sensor malfunction warning appeared on the dashboard. After some initial confusion, my workshop diagnosed the problem as a loose connection in the wiring harness leading to the sunlight sensor. The sensor itself was functioning correctly, but the faulty cable connection was causing intermittent signal disruptions. The total repair cost was 95€, which covered the diagnostic work and fixing the connection. The solar sensor plays a crucial role in the HVAC system by adjusting temperature and airflow based on incoming sunlight intensity. When these sensors malfunction or have connection issues, it typically leads to inconsistent heating performance. Before suggesting specific solutions, could you share: Are there any specific error codes showing up? Does the heating performance vary depending on weather conditions? Have you noticed any other electrical issues in the vehicle? When did these symptoms first appear? This additional information would help determine if your issue matches what I experienced with the cable connection problem.

The temperature sensor issue persists even after my latest service at 34074km. The workshop checked for error codes and found sensor fault P0116 which points to an HVAC temperature sensor malfunction. The heating performance definitely varies with outside conditions, working better on cloudy days than in direct sun, suggesting the sunlight sensor might be involved. When the automotive sensor readings are erratic like this, I was wondering if recalibration might fix it or if I should prepare for a full sensor replacement. The inconsistent heat output started about two weeks ago.

Based on your description, this sounds remarkably similar to what I experienced in my Tiguan. The P0116 code combined with the weather-dependent performance strongly suggests a sunlight sensor calibration issue rather than just a wiring problem like I initially had. In my case, after the wiring fix didnt fully resolve it, the workshop performed a complete sensor calibration procedure on both the solar sensor and temperature sensors. This corrected the erratic HVAC behavior. However, they warned me that if calibration doesnt fix it, the sensor unit itself might need replacement. The fact that your car heating works better on cloudy days matches the pattern exactly, when the sunlight sensor provides incorrect readings, it throws off the entire HVAC temperature calculation. My recommendation would be to: 1. Request a specific calibration of the automotive sensor system 2. Have them verify the solar sensor values during both sunny and cloudy conditions 3. Check if the temperature readings stabilize after calibration If recalibration doesnt work, replacement costs typically run 200-300€ for the complete sensor unit. But start with calibration since its the less expensive option and fixed the issue in my case. One additional note: check your coolant levels. Low coolant can sometimes trigger similar symptoms and sensor errors, and its worth ruling out before diving into more complex sensor repairs.

Given the automotive sensor readings and guidance about calibration, I tried having my workshop perform the recommended sensor calibration procedure first. Unfortunately, even after the HVAC sensor recalibration, the temperature sensor continues showing fault code P0116 and the heating remains inconsistent. Following their diagnostic process, they confirmed the solar sensor is indeed malfunctioning and needs replacement, it's not just a calibration issue. The parts and labor quote came in at 275€, which matches the cost range mentioned. I've scheduled the repair for next week. Thanks for helping identify that the weather-dependent performance pointed to a sunlight sensor problem rather than just a general temperature sensor fault. The systematic approach of trying calibration before replacement helped rule out simpler fixes. For others who might have similar issues, the key diagnostic sign was definitely how the heating worked better on cloudy versus sunny days.