VW Polo Multiple Electrical Failures After Service Visit

Had a similar situation with my 2016 VW Golf TDI at 145000km. The symptoms match exactly what you describe, multiple electrical system failures and comfort features malfunction. The initial automotive sensor diagnostic showed humidity sensor issues, but after thorough testing, the root cause was a corroded main wiring harness connector near the firewall. The humidity sensor reading was just a symptom, not the core problem. The repair required: Complete inspection of the wiring harness, Cleaning of all connector pins, Replacement of the damaged connector section, Full sensor calibration of affected systems This was classified as a serious electrical issue since it affected multiple vehicle systems. Leaving it unrepaired could lead to more severe electrical problems and potential safety concerns. The repair needed specialized diagnostic equipment to properly identify all affected circuits. After fixing the connector issue, all systems including AC, mirror heating, and washer nozzles returned to normal operation, and the sensor readings stabilized. Would strongly recommend having a complete electrical diagnostic done rather than just replacing the humidity sensor based on the initial error code.

Thanks for sharing this experience. I had exactly those problems with my 2018 Polo last winter. The dashboard warning kept showing up and the visibility was terrible due to none of the heating elements working. The diagnostic also pointed to the humidity sensor first, but like your case, it turned out to be a wiring harness problem affecting multiple electrical systems. Good thing I got a second opinion because simply replacing the sensor would not have fixed it. Just wondering, what was your final repair cost? And has everything stayed working properly since the fix? My AC occasionally still acts up but the other systems are fine.

After getting it properly diagnosed and fixed, the total cost came to 95€ for repairing the faulty cable connection affecting the climate control systems. The visibility issues and windshield fogging problems completely disappeared once they corrected the automotive sensor connections. Since the repair six months ago, everything has worked flawlessly, including the AC, mirror heating, and washer nozzles. The electrical issue turned out to be much simpler than initially feared. No more dashboard warnings or sensor errors. For your occasional AC problems, it might be worth checking the connections again. Sometimes these electrical issues can be intermittent if there are still loose contacts in the system. A proper diagnostic scan should reveal if the climate control module is receiving inconsistent signals. The key was finding a mechanic who looked beyond the initial humidity sensor error code to identify the actual wiring problem. Getting this kind of electrical issue properly diagnosed the first time saves both money and frustration in the long run.

Thanks for the helpful advice. I finally got this sorted out. Took it to a certified electrical specialist who did a complete diagnostic scan. Like many of you mentioned, the humidity sensor malfunction was just a symptom of a bigger issue. The mechanic found corroded wiring connections near the firewall, similar to what others experienced. The total repair came to 280€ which included: Full electrical system diagnosis, Wiring harness repair, Connector replacement, System recalibration Been about 2 weeks since the fix and all the comfort features are working perfectly again. No more dashboard warning lights or electrical issues. The AC runs great and the washer nozzles spray like new. Really glad I asked here first and got that second opinion instead of just replacing the sensor. Saved me from paying for unnecessary parts and repairs. The automotive sensor readings are all normal now and the car feels like new again.