SM5 Rear Ventilation Flap Issue

Sounds familiar! I drive an SM5 too. Had a similar issue with the rear vents. The flap actuator controls the airflow. If the connector is loose or the wiring faulty, it throws everything off. Have you checked the wiring harness and plug going to the rear climate control? It's a pain to get to, but might be worth a look.

Could you clarify where exactly I should be looking for this wiring harness and plug?

In my case, it was behind the center console, near the rear passenger footwell. You'll probably need to remove some trim panels to get good access. Honestly, it might be a hassle without the right tools and knowledge. If you mess with the airbag system by accident, it could be dangerous and expensive. Since it’s a climate control issue, are you sure it is the easiest thing to fix yourself? Especially since that is a newer car, my advice would be to get it to a real workshop.

I will take the vehicle to a workshop. The error memory was read, and the defective cable or plug connection confirmed. Repair cost: 95€.