EQC rear window heating issue

I have a similar Mercedes EQC. I had analogous symptoms last winter – rear window heating failed, and the front wasn't great. Have you checked the auxiliary battery? It's like a smaller version of the main battery, handling some of the lower-draw functions. When mine started failing, it caused all sorts of weird electrical issues. It's less 'main power' and more like a glitch in the system – everything seems off. Does your car have any issues when starting or pre-heating?

That's a great analogy, describing it like a glitch in the system! I appreciate the insight on the auxiliary battery. Beyond starting or pre-heating issues, what other 'weird electrical issues' did you notice with your EQC when the auxiliary battery was failing? I'm trying to determine if it's worth investigating further myself before needing defroster repair.

Besides the window issue, my EQC had some random errors popping up on the display – nothing consistent, just brief warnings that would disappear. The auto defrost seemed less effective overall, and the range displayed was fluctuating more than usual. Honestly, though, the window heater issue was the most obvious sign something was amiss. If you're seeing similar things, it’s strongly pointing towards battery issues. I ended up taking mine to a shop, and they confirmed it pretty quickly. Best of luck with the heating coil!

Thanks for confirming that your experience aligns with what I'm seeing, especially with the auto defrost. I appreciate you taking the time to describe the other symptoms you encountered; that's very helpful. I'll bring it in for a proper diagnosis, sounds like it's time to get it checked out. I'll post here when they confirm the source of the window heater problems.