VW Golf Window Defroster Failures, DIY Fix Tips

Had similar window demister problems on my 2012 Golf 1.4 TSI. The auto defrost failure started gradually, first with weak heating on the rear window, then complete failure of both front and rear systems. The root cause turned out to be more than just a blown fuse. The charging system was failing, causing the battery to discharge below optimal levels. When the battery voltage drops too low, the car defrost systems are among the first functions to get disabled to preserve power. The repair required: Full diagnostic scan, Alternator replacement, New battery installation, Testing of all thermal window circuits This was a serious repair job taking nearly a full day at the workshop. The car defrost system now works perfectly after fixing the charging system issues. Worth noting that putting off this repair can lead to more electrical problems, as a weak charging system affects multiple components. The symptoms match what you describe, error codes and simultaneous failure of both heating elements. Recommend getting the charging system checked before replacing any heating components.

Thanks for sharing that detailed repair info on your Golf. Really good to know about the connection between charging system and defrost problems since my heating coil issues sound very similar. Quick question, do you remember roughly what you paid for the full repair? Also wondering if you had any other electrical gremlins pop up since getting it fixed? Trying to budget for my upcoming repair and want to make sure I address everything while its in the shop.

Glad I could share my repair experience. Got my car back from the mechanic last week, and the rear defroster is working perfectly now. The root issue was exactly what I suspected, a heavily discharged battery that needed replacement. The total repair came to 290€, which covered the new battery, system testing, and labor. Much cheaper than I initially feared since no alternator work was needed. The car defrost system immediately started working properly once the new battery was installed. No other electrical issues have appeared since the repair. All thermal window functions are back to normal, and the error codes have completely cleared. The mechanic did a thorough check of the entire charging system while it was in, which gave me peace of mind that the heating issue was properly resolved. If your symptoms match mine, focusing on the battery and charging system first could save you from unnecessarily replacing defroster components.

Thanks for the advice. Finally got my Golf back from the shop yesterday after the defroster repair. You were spot on about checking the charging system first. Turns out my alternator was putting out weak voltage, slowly killing the battery over time. The window demister problems were just a symptom of the bigger electrical issue. Total bill came to 485€ for new alternator, battery, and labor. The auto defrost now works great on both front and rear windows. Really glad I asked here first, saved me from getting ripped off replacing window heating elements that werent actually faulty. The mechanic I found did good work, threw in a free electrical system check, and even showed me the old alternator to explain the wear. Way better experience than my last repair shop visit. No error codes since the fix and all electrical systems are working normally. Thanks again for helping me avoid an unnecessarily expensive repair job.