Mini One Heating Issue

Ugh, that's a bummer! Low heat output combined with a stored error code definitely points to an issue within the HVAC unit, specifically related to air distribution. Have you checked the blower motor resistor? Sometimes a faulty resistor can cause erratic blower behavior which might indirectly impact air distribution. It's usually located near the blower motor, accessible from the passenger footwell. Also, is the air circulation working correctly? Can you hear the flap actuating when you switch between fresh air and recirculation?

I haven't checked the blower motor resistor, but that's a good shout. Where exactly is the blower motor located in this thing? And how would I diagnose a faulty resistor anyway? As for the air circulation, I can hear something happening when I switch it on and off, but I'm not sure if the flap is actually moving as it should.

Okay, if you can hear something happening when you switch the air circulation but aren't sure if the flap is moving, that could very well be your issue. The fact that you have a stored error code relating to the air distribution flap kinda confirms it. Realistically, it's probably best to get it diagnosed properly at a workshop. Messing with the climate control and HVAC unit without the right tools can be a nightmare. They can pinpoint exactly what's going on with the air distribution system.

Appreciate the input. Ended up biting the bullet and having it checked out. Turns out it was indeed the air distribution flap motor, and the connection was faulty as suspected. 95€ later, and the climate control is working as it should. Thanks again!