VW Up Humidity Sensor Causing Multiple System Failures

I had similar electrical issues with my 2014 VW Polo last winter. As someone with some experience working on VWs, these symptoms immediately reminded me of my situation. The dashboard warning lights and multiple electrical failures pointed to a sensor calibration problem. My workshop found that the main wiring harness connector to the humidity sensor had corroded, causing intermittent failures across several systems. The automotive sensor itself was fine, but the cable connection had deteriorated. The fix involved cleaning the connector pins and replacing the damaged section of the wiring harness. Total cost was 95€ for parts and labor. Since the repair, all systems have worked perfectly, including the AC, washer nozzles, and mirror heating. To help diagnose your specific case, could you share: Have you noticed any windshield fogging issues? Does the problem get worse in wet weather? Did the issues start gradually or all at once? Have you had any recent work done near the sensor area? The symptoms match what I experienced, but getting these details would help confirm if your Up has the same underlying electrical issue.

Had my last service at 85000km and can confirm these exact symptoms. The humidity sensor diagnostic showed multiple error codes. The climate control system was seriously affected, especially during cold starts. The repair shop cleaned and recalibrated all car sensors in the front area but the issues came back after 2 weeks. They finally traced it to a damaged wire harness connector near the windshield that was causing electrical issues across multiple systems. After replacing the connector and relevant wiring sections (180€ total), all visibility systems including mirrors and washer nozzles are working properly again. The dashboard warning lights have also cleared completely. Important to note, make sure they check the ground connection when replacing the harness. The first attempt failed because they missed a corroded ground point.

Yes, that corroded ground connection is exactly what caught me out too. The first repair on my Polo didnt last because the workshop only replaced the visible damaged wiring without checking the ground points. The recurring issues with the climate control system and sensor calibration failures make perfect sense now. The multiple error codes kept coming back because the poor ground connection was affecting the entire sensor network, particularly the humidity readings. A proper fix involves: 1. Full inspection of all ground points near the windshield 2. Complete cleaning of sensor connectors 3. Testing visibility systems across different temperatures 4. Verifying climate control operation after cold starts My repair cost 95€ initially, but the proper fix including all ground points ended up at 175€. Still, its worth doing properly to prevent the dashboard warning lights from returning. The most reliable test after repair is checking if all systems (AC, washer nozzles, mirror heating) work consistently during the first cold morning start. If the car sensor network is properly grounded, there should be no more intermittent failures.

Thanks for all the helpful responses. Just wanted to close this thread and confirm the final solution for others who might have similar issues. The electrical issues were indeed caused by corroded wiring connections affecting the humidity sensor system. After a thorough diagnotic scan showing stored errors, the repair shop found multiple failing ground points. The windshield fogging problems and inconsistent climate control were key symptoms pointing to the sensor calibration issues. The complete repair involved: Replacing the main wiring harness section (180€), Cleaning all sensor connections, Fixing 3 corroded ground points, Running full system diagnostics All dashboard warning lights are now clear, and every system works perfectly, AC, washer nozzles, and mirror heating included. The visibility systems remain stable even during cold starts, proving the electrical issue is fully resolved. For anyone facing similar symptoms, make sure your repair shop checks all ground connections when dealing with sensor-related electrical issues. It saved me from needing multiple repair attempts.