Audi S4 Mirror Heater Troubleshooting Fix Guide

Had the exact same issue on my 2002 Audi A4. Being somewhat experienced with car electronics, I first suspected a simple fuse issue like you did, but it turned out to be trickier. After checking all the obvious points, I took it to a workshop where they diagnosed a faulty wire connection between the mirror heating control unit and the mirror itself. Winter driving was becoming a real hassle with foggy mirrors, so I had them fix it right away. The car mirror repair involved accessing the door panel and replacing a damaged connection cable that had worn through over time. Including diagnostic work and parts, the total repair cost was 95 Euro, which seemed fair given the detailed work involved. Before I can provide more specific advice about your case, could you share: Whether both mirrors are affected or just one side, If you notice any intermittent function, Whether other electrical functions in the door (window, mirror adjustment) work normally, If the issue started suddenly or gradually This would help determine if your S4 has the same electrical fault mine had or if its something different in the mirror heating system.

Just had my last service at 94661 KM and faced this exact rearview mirror heating problem. Both mirrors are completely dead and other door functions work fine. The heater element failed suddenly during a cold weather spell last month. After some testing, the workshop found corroded wiring connectors feeding the mirror heating circuit. The electrical fault was causing inconsistent power delivery to both sides. Total fix came to 180 Euro including new connectors and labor to access the door panels. Would recommend getting a proper diagnosis since these car electronics issues can have multiple causes. The repair cost is worth it considering how essential clear mirrors are for safe winter driving.

Thanks for the follow-up details about your S4. My A4 had very similar symptoms, complete mirror heating failure during cold weather. The corrosion issue you found matches what I experienced, though yours affected both sides while my heater element issue was initially only on the driver side. The repair cost difference makes sense since you needed work on both rearview mirror assemblies. 180 Euro is still reasonable considering the complexity of accessing those door panel connections. The previous owner of my car had apparently tried a DIY fix which made the corrosion worse, so having proper workshop repair was definitely the right call. Good to hear all other door electronics worked normally, that was a key diagnostic sign pointing to localized mirror heating wiring rather than a central control module problem. These connectors seem prone to moisture damage, especially after years of winter weather exposure. For anyone else facing similar heating issues, documenting the mileage like you did (94661 KM) helps identify when these electrical faults typically develop. Early diagnosis prevents further corrosion damage and keeps repair costs manageable.

Good to close this thread with updated findings. After completing the mirror heating repair on my S4, I can confirm it was definitely the corroded wiring connectors causing the vehicle safety issue. The 180 Euro cost covered both sides and was money well spent for reliable winter driving. The repair timing at 94661 KM might help other owners anticipate when their car electronics could develop similar issues. The cold weather definitely exposed the problem, but the workshop confirmed the corrosion had been building up gradually. For reference, all door functions except the mirror heating worked perfectly throughout, which helped narrow down the diagnosis. Having clear rearview mirrors is essential for safe driving, so I would encourage getting any heating faults checked promptly rather than waiting for more extensive damage to develop. Thanks to everyone who shared their experience with similar mirror heating problems. The workshop diagnosis matched several other cases here, showing these wiring issues are a known weak point requiring proper repair.