Audi A6 Defrost System Failure: Heating Grid Dead

Having dealt with a similar window heater problem on my 2005 Audi A4 2.0, I can share some insight based on moderate experience with these systems. The symptoms you describe match what I encountered, complete failure of both front and rear window demister functions. The heating issue turned out to be battery-related in my case. When the battery charge drops too low, the heating coil systems often shut down to preserve power for essential functions. My repair involved: Full battery diagnostic test, Replacement of the failing battery, System reset to clear error codes, Testing all heating elements after replacement Total cost was 290 Euro including parts and labor. The workshop confirmed this is a somewhat common issue with these models when batteries start failing. Before jumping to conclusions though, could you share: Has the battery warning light appeared? Does the car have any starting issues? Are there any other electrical issues present? Have you noticed dimming lights? This would help determine if your issue matches what I experienced or if its potentially a different root cause.

My mechanic diagnosed a blown fuse connected to the rear defroster circuit and found corrosion on some wiring connectors. A thorough cleaning of the connections and fuse replacement resolved the window defrost failure. Last service was at 171194 KM with a full electrical system check. The car defrost system is working perfectly now, with both front and rear heating elements functioning as they should. Total repair cost ran about 180 Euro which seems reasonable for resolving this type of heating issue.

Thanks for the update on your A4 defrost system repair. Its good to hear you got it sorted for a reasonable cost. I wish my heating coil repair had been that straightforward. When I had that similar thermal window problem on my A4, the battery diagnosis was just the start. After replacing the battery, the auto defrost system still failed intermittently. The rear defroster would work sometimes but not consistently. Turned out I also had corroded connectors, but they were harder to access in my case. The workshop had to remove several interior panels to reach them. Plus, they found two damaged heating elements that needed replacement. My total came to about 450 Euro. Your repair cost of 180 Euro for the fuse and connector cleaning is actually quite good for this type of heating issue fix. The fact that all your heating elements were still intact saved you from the more extensive repairs I needed. Keep an eye on those connections though, in my experience with these models, corrosion can return if moisture finds its way back into the system.

No heating problems at all now that the repairs are complete. The window demister is performing exactly as it should in both front and rear. Really glad I checked here first since it helped me understand what to expect at the workshop. The defroster repair turned out to be much simpler than I feared, just that blown fuse and some corroded connections rather than failed heating coil components. Regular maintenance definitely seems key with these systems. Given how reasonable the 180 Euro repair cost was compared to more extensive thermal window repairs others have mentioned, I feel quite fortunate. Thanks everyone for sharing their experiences and helping me understand the likely causes of these heating issues.