A3 Mirror Heater Failure: Owner Seeks Repair Cost Tips

Had the same issue on my 2020 A4 2.0T last winter. The rearview mirror heating failure turned out to be a faulty wiring connection where the harness meets the mirror assembly. The electrical fault was causing the temperature control module to register an error but not engage the heating element. The repair involved accessing the headliner area to reach the connection point. While the mirror unit itself was fine, the wire insulation had worn through, creating an intermittent short. This is actually a common wear point in cold weather conditions, especially when the mirror gets adjusted frequently. This wasnt a serious safety issue, but definitely needed fixing to maintain proper visibility. The repair required disconnecting the battery, replacing the damaged section of the wiring harness, and clearing the stored error codes. Most important was ensuring the new connections were properly sealed to prevent future moisture-related problems. Vehicle safety depends on clear visibility, so while not immediately dangerous, its best to address this before winter conditions worsen. The job typically takes 2-3 hours for a qualified technician to complete properly.

Thanks for sharing your experience with the wiring issue. I had nearly identical problems with my A3 last month. The winter driving conditions really highlighted how critical a working rearview mirror heater is. Just wondering, do you remember the final repair cost for your fix? Also curious if youve had any other temperature control issues pop up since the repair? My local shop quoted a mirror replacement which seemed excessive, but Im trying to compare costs before deciding where to take it.

Actually took my A4 in last week for the repair. The car electronics diagnostic showed it was just a damaged wire connection near the mirror housing, exactly like you described. Total bill came to 95 Euro for fixing the faulty connection, which seems fair considering the work involved. No temperature control problems since the repair. The rearview mirror heating now works perfectly during winter driving conditions. Pretty relieved it didnt need a complete mirror replacement like your shop suggested. That would have been unnecessary and much more expensive. The repair involved reconnecting and properly sealing the wiring, took about two hours of labor. Worth checking other shops that might diagnose the actual issue rather than defaulting to replacing the entire mirror assembly.

Thanks for the helpful advice. I ended up taking it to a different shop that properly diagnosed the electrical fault. Like many of you suggested, it was just a wiring issue near the mirror housing, no need for a complete mirror replacement after all. The total repair cost was 120 Euro, which included diagnosing the problem, fixing the wiring connection, and clearing the error codes. The rearview mirror heater now works perfectly again. The whole job took about 2 hours and the technician showed me exactly where the wire had worn through. Really glad I got a second opinion instead of paying for an unnecessary mirror replacement. The temperature control system works great now and I feel much safer driving in cold conditions with proper mirror defrosting. Definitely learned my lesson about getting multiple quotes for electrical issues like this.