Seat Mii mirror heating not working

Mirror heating issues can be tricky. From my past experience with a similar problem on an older vehicle, it might indeed be a defective cable or plug connection. However, before jumping to conclusions, have you checked the relevant fuse for the mirror heating circuit? A blown fuse is a simple fix and often overlooked. Also, is there any sign of damage to the car mirror itself? Even minor cracks can sometimes affect the temperature control and heating element. If the fuse is fine and there's no visible damage, then the error memory likely points towards a deeper electrical fault.

I checked the fuses, they seem fine. No visible damage to the car mirror either. How can I check the cable or plug connection myself?

Since the fuses are okay and there's no visible damage, checking the cable or plug connection yourself might be difficult without the right tools and knowledge. You'd need to access the wiring behind the car mirror, which can be fiddly and potentially damage other components if not done carefully. Considering the error stored in the memory and the potential for a deeper electrical fault, I'd advise against attempting a DIY fix. It might be best to take it to a workshop to avoid further complications and ensure vehicle safety.

Took it to a local garage. They confirmed the electrical fault and replaced the car mirror. The bill came to 95€. All good now.