VW Polo Light Sensor Issues Cause Multiple Failures

I had a similar issue with my VW Golf TDI 2017. As someone with moderate experience working on cars, I first noticed the light sensor acting up before other systems started failing. The root cause turned out to be bubbles forming under the gel pad where the rain detection and light sensor components are mounted on the windshield. This caused multiple malfunctioning sensor readings and unusual activation of lights and wipers. The repair was straightforward but required specialized equipment. My workshop removed the old sensor unit, cleaned the mounting area thoroughly, and installed a new gel pad with the sensor properly calibrated. Total cost was 62€ for parts and labor. Before suggesting specific solutions, could you share: Has the windshield been replaced recently? Are there any visible marks or damage around the sensor area? When did these issues first appear, gradually or suddenly? Have you noticed any correlation with weather conditions? This information would help determine if your issue matches what I experienced. The sensor fault symptoms sound very similar, but these additional details would confirm if we are dealing with the same problem.

Thanks for sharing your experience. My car has 78042km and was last serviced 2 months ago. The issues appeared suddenly after heavy rain last week. Looking at the windshield more closely, there is a small bubble visible near the auto sensor mount behind the rearview mirror. The windshield is original and hasnt been replaced. The electrical fault seems to be getting worse, now the rain sensor activates the wipers out of nowhere even in dry conditions. The auto headlight system also turns on and off unpredictably. Given the similarities to your case, it sounds like the sensor unit and gel pad need replacement. Good to know the repair costs are reasonable. Will book it in to have the car electronics checked and rain detection system replaced.

Based on your description, this definitely matches the sensor fault pattern I experienced. Those unusual wiper activations and unpredictable headlight behavior are classic symptoms of a failing rain-light sensor unit, especially after exposure to heavy rain. The bubble you noticed near the sensor mount is a clear indicator that moisture has compromised the gel pad seal, exactly what happened with my car. The electrical fault typically worsens because water gradually seeps into the sensor housing, affecting the car electronics more over time. Since your car has similar mileage to when mine failed, and considering its the same issue, you should expect a similar repair process. The malfunctioning sensor replacement took about an hour at the workshop. They didnt just swap parts, they also recalibrated the new unit to ensure proper rain detection and light sensing functions. One tip from my experience: make sure they completely clean and dry the mounting area before installing the new sensor. Any residual moisture can cause the same issues to return. The total repair including parts, labor and calibration should be in the 60-70€ range.

Thanks everyone for the insights. After getting my car checked at the workshop, I can confirm it was indeed the light sensor causing all these issues. The bubbled gel pad was the culprit, just as suggested. The repair took about an hour and cost 65€ total. They cleaned the mounting area thoroughly, installed a new sensor unit with fresh gel pad, and calibrated all systems. The car components are now working perfectly, no more unusual wiper activation or headlight malfunctions. The auto sensor functions are back to normal, and the speedometer lighting is also fixed. For anyone else experiencing similar sensor fault issues, definitely check for bubbling around the sensor mount first. Getting it fixed early prevents more extensive electrical problems from developing. Really glad to have gotten advice here before taking it in. The repair was exactly as described and the cost was in line with what was quoted. All the automated systems are now working as they should.