VW Tiguan Rear Defroster Failure: Diagnosis Tips

Had the same issue on my 2019 VW Golf GTI. The rear defroster stopped working completely during winter, and the thermal window heating showed an error code. Initial diagnosis revealed a damaged heating coil connection at the bottom of the rear window. The car defrost system failure was more complex than expected. Testing showed both a faulty relay and corroded terminals where the defroster grid connects to the power supply. These issues often appear together as the system ages, especially when the car regularly faces cold weather. The repair required: Replacing the defroster relay, Cleaning and repairing the heating grid connections, Testing the entire defrost circuit, Updating the control module software This turned out to be a serious electrical system issue that could have led to more problems if left unaddressed. The defroster repair took about 4 hours to complete. Would recommend getting it fixed soon, as failing heating elements can indicate deeper electrical problems. The symptoms match exactly what you describe in your Tiguan. These heating system faults are common in VW models from that generation.

Thanks for sharing your experience. Your defroster fault sounds identical to what I am dealing with on my Tiguan right now. Really helpful to know about the relay and connection issues you encountered. Just curious, do you remember the total repair cost for all that work? Also, has the auto defrost system been working reliably since the fix or have you noticed any new issues? My heating coil seems particularly weak on the passenger side of the rear window, so I am trying to gauge if I am looking at a similar comprehensive repair.

Thanks for asking about the repair outcome. After having the rear window heating fixed, everything has been working perfectly for several months now. The window demister activates quickly and heats evenly across the entire rear window surface. The total cost came to 290€, which covered diagnosing and fixing the heavily discharged battery that was causing the heating system problems. This was significantly less than I initially feared when the heating coil issues first appeared. The uneven heating you noticed on the passenger side actually matches what I experienced before the repair. The key was getting a thorough electrical system check, as the faulty rear window defroster turned out to be a symptom of the battery problem rather than damaged heating elements. Since the repair, the defrost function works reliably in all weather conditions. Based on your description, it sounds like your Tiguan might have the same underlying issue. Would definitely recommend getting a full electrical diagnosis rather than just focusing on the heating issue alone.

I took your advice and got my Tiguan checked out at a different repair shop today. You were spot on about getting a full electrical diagnosis. The mechanic found similar issues to what you described, a failing relay and some corroded connections at the base of the rear window defroster. The total repair came to 310€, which included replacing the relay, cleaning all the heating coil connections, and testing the entire electrical system. The thermal window heating is now working perfectly, both front and rear defrosters heat up quickly and evenly. No more error codes showing up on the dash either. The mechanic mentioned that these heating system problems are pretty common in VWs from this era. Really glad I got it sorted before winter hits. The whole repair only took about 3 hours, and the shop even found and fixed a loose ground wire that was contributing to the problem. Much better experience than my previous attempts to get this fixed.