BMW Window Heater Failure: DIY Help Needed

Hey there. Had a similar issue with my 2007 BMW 5 Series diesel last winter. Initially thought it was just a blown fuse, but turned out the battery was heavily discharged. The car's electrical system was drawing more power than usual to compensate for the weak battery, causing the heating elements to malfunction. When I took it to the garage, they did a full diagnostic. The battery had basically reached the end of its life and wasn't holding charge properly anymore. This was affecting multiple electrical systems, not just the heating. They had to replace the battery and reset the electrical system. It was a serious issue because a failing battery can damage other electrical components if left unchecked. Plus, you really don't want heating problems when you need them most. Before heading to a shop, you might want to check the fuses first, there's usually one specific to the rear window heating. But given the multiple heating issues and error code, it's likely something more significant like what I experienced with the battery system.

Thanks for sharing your experience! That's really helpful since our situations sound pretty similar. Just curious, do you remember roughly how much you ended up paying for the whole fix? Also, has everything been working fine since then, or have you noticed any other electrical quirks popping up? I'm trying to get an idea of what I might be looking at cost-wise and whether I should expect any follow-up issues.

Hey again! Just wanted to follow up since you asked about the costs. I paid 290 € for the battery replacement and system reset. And honestly, it was totally worth it, everything's been working perfectly since then, including the rear window heating that was giving me grief before. Such a relief! After they installed the new battery and reset everything, all those electrical quirks disappeared completely. It's been over a year now, and I haven't had a single issue pop up. The rear defroster kicks in right away when I need it, and all other electrical systems are running smoothly. I know it might seem a bit pricey at first, but considering how many problems a bad battery can cause, I'd say it's better to get it sorted properly. Plus, it's way cheaper than having to fix multiple electrical components if you let the problem drag on too long. Just make sure you go to a shop that really knows BMWs, it makes a huge difference when they understand these specific electrical systems. Hope this helps with your decision!

Thanks for the detailed update! Finally got my car checked out yesterday. You were spot on, it turned out to be a battery-related issue, but my case was a bit different. The mechanic found corroded battery terminals and some damaged wiring. The total fix came to 340 € including a thorough electrical system check. The guy was really great, actually. He showed me exactly what was wrong and explained everything clearly, such a different experience from my last mechanic! Picked up the car this morning and wow, what a difference! The rear window heater kicks in instantly now, and that annoying error code is gone. Really glad I asked here first. Your advice helped me know what to look out for and gave me confidence to try a new mechanic. Thanks again for all your help, definitely saved me from potentially bigger problems down the road!