VW Beetle Climate Control Issues & Sensor Malfunction

I had a similar issue with my 2016 VW Golf TSI last winter, and having some experience with HVAC systems in cars, I can share what worked for me. The symptoms were nearly identical, weak heat output and unreliable temperature sensor readings. After taking it to my regular workshop, they diagnosed a faulty connection between the daylight sensor and the climate control module. The automotive sensor itself was fine, but the wiring connection had deteriorated over time. The repair involved checking all HVAC sensor connections and replacing a damaged wiring harness that connected to the temperature sensor assembly. Total cost was 95€, including labor and parts. Since the fix, the heating system has worked perfectly. To provide more specific advice for your case, could you share: Does the issue occur immediately after starting the car or only after driving for a while? Are you getting any specific error codes? Have you noticed if the problem is worse during particular weather conditions? Did you have any recent work done on the climate control system? These details would help determine if your Beetle is experiencing the same connection issue I had with my Golf.

After 97179km and my last service in November, this heating issue started occurring. The problem appears right after cold starts and persists throughout the drive. Getting error code P0116. Running a basic scan showed the solar sensor might be failing, which matches the symptoms you described. Since posting, I checked for obvious loose connections. Found nothing visible, but noticed the heating is slightly better when driving in cloudy conditions, suggesting the daylight sensor and temperature sensor might indeed be miscommunicating with the climate control module. Based on your experience, it sounds like I could be dealing with the same sensor calibration issue. Did your repair shop mention how they tested the wiring connections specifically? Trying to gather as much info as possible before taking it in.

Thanks for providing those additional details about your Beetle. The behavior you described with better performance during cloudy conditions strongly matches what I experienced with my Golf. When my sunlight sensor started acting up, the workshop used a specialized diagnostic tool to test the signal strength between the sensor and the climate control module. The connection degraded particularly when exposed to temperature changes, which explains why cold starts triggered the issue. The P0116 error code points to engine coolant temperature sensor circuit range issues, but in my case, and likely yours, the root cause was the faulty wiring affecting multiple sensor inputs. The car sensor system gets confused when receiving conflicting temperature data. My repair actually revealed corroded pins in the daylight sensor connector, which caused intermittent signal problems. The sensor calibration was fine once they replaced the wiring harness and cleaned the connection points. Given your mileage and the timing after the service, I recommend having them specifically check: The wire harness connecting the temperature sensor cluster, The ground connection points for the sensor system, The connector pins for signs of corrosion The repair costs should be similar to what I paid unless they find additional issues during inspection.

Thanks for the detailed breakdown of your Golf repair experience. Knowing the P0116 code links to the engine coolant temperature circuit helps explain why my Beetle heating acts up during cold starts. The behavior during cloudy conditions makes more sense now too, clearly the sunlight sensor is part of the equation. I called my usual shop and booked it in for next week. Mentioned the fault detection process you described and asked them to check those specific points, the wiring harness, ground connections, and connector pins. They confirmed they have the right diagnostic tools to test the HVAC sensor signal strength. The quoted price range matches what you paid, around 90-100€, assuming they find similar wiring issues. Given how the symptoms match your case almost exactly, especially the daylight sensor connection problems, I feel much more confident about getting this fixed now. Really appreciate you sharing those repair details. Will update once the shop completes the diagnostic work and confirms whether the sensor calibration issues match what you experienced.