Caddy's Fog Sensor Triggers Multiple System Failures

As a VW Polo GTI 2018 owner, I encountered a similar fog sensor malfunction that caused multiple system failures. The automotive sensor cluster behind the rearview mirror was the root cause, affecting climate control and related functions. The windshield fogging sensor malfunction triggered cascading electrical issues, impacting the spray nozzles and mirror heating. The dashboard warning initially suggested a simple sensor calibration problem, but diagnostic testing revealed a damaged wiring harness connector at the sensor base. The repair required: Complete removal of the sensor cluster, Replacement of the wiring harness, Recalibration of the rain/light/fog sensor unit, System reset to clear stored error codes This was a serious issue since the faulty sensor affected multiple vehicle systems. The repair took a full day at the workshop due to the complexity of accessing and replacing the components behind the mirror housing. After repair, all systems returned to normal operation, including: Climate control functionality, Proper spray nozzle operation, Mirror heating system, Automatic light control Based on these symptoms, your Caddy likely has a similar wiring connection issue rather than just a sensor calibration problem.

Thanks for sharing your experience with the sensor repairs. I had a similar humidity sensor malfunction in my 2019 VW Caddy that caused the climate control and related systems to fail. Your description matches what happened with mine exactly, especially the windshield fogging sensor issues. After reading about your repair process, I am curious, do you remember the total cost for fixing everything? Also, has everything worked perfectly since the repair or have you noticed any other small issues popping up? Would be helpful to know since I am still dealing with occasional error messages, even after the initial fix at my local shop. The automotive sensor cluster repair they did might not have been as thorough as yours.

After getting the fog sensor fixed at the shop, everything has worked flawlessly in my GTI. The total repair cost was 95€, which mainly covered fixing a faulty cable connection in the automotive sensor assembly. Much simpler fix than expected. The electrical issues and dashboard warning lights completely disappeared after addressing that connection problem. The windshield fogging sensor now works correctly, and all the related systems, climate control, spray nozzles, and mirror heating, function perfectly even in cold weather. Since you mention still getting error messages, I recommend having them check specifically for loose connections in the sensor wiring. My malfunction turned out to be just a bad plug connection rather than a full sensor replacement. Getting this fixed properly the first time saved dealing with recurring issues later.

Thanks for the advice. I finally got this resolved after taking it to a different shop that specializes in VW electrical systems. The visibility was terrible with all the fogging issues, so I knew I had to get it fixed properly. Turns out the humidity sensor was damaged, causing the climate control malfunction. The repair involved: Replacing the entire sensor unit, New wiring connection, Full system diagnostic check, Recalibration of all affected components Total cost came to 320€ but worth every cent. The automotive sensor cluster now works perfectly, no more error codes or system failures. Climate control maintains proper temperature, spray nozzles work great, and mirror heating activates normally in cold conditions. Much better experience than my first mechanic visit where they just tried resetting the system without properly diagnosing the root cause. Sometimes paying more for specialized expertise saves money in the long run.