LX Rearview Mirror Heating Failure

That's a frustrating issue to encounter, especially on a vehicle as new as yours. I experienced something similar with my previous car, a 2016 model, and it turned out to be a corroded connector within the door. However, given that you've already checked the wiring harness, is it possible that the issue lies with the heater element itself within the mirror? Have you attempted to measure the resistance of the heating element to confirm its functionality?

Good shout on the heater element resistance. I haven't measured that yet. Where's the easiest access point to check that? Don't want to butcher the mirror assembly.

Considering the complexity of modern rearview mirror assemblies and your vehicle still being under warranty, it might be prudent to consult with a qualified technician. While I understand the inclination to diagnose the issue independently, tampering with the mirror components could potentially void the warranty or lead to further complications. It is possible that a diagnostic scan at a workshop might reveal more specific information regarding the fault.

Yeah, you're right. Bit the bullet and took it in. Turned out to be a loose plug on the driver's side mirror. They re-seated it, cleared the code, and I was out the door for 95€. Thanks for the sanity check!