Its an NTC fault. Think its the one in air duct. Check Fan is working properly, you have to bypass freezer door switch to see if it runs ok, the fans give trouble. Also i’ve had some of the thermistor seals let in moisture. Silicone smeared on seal should sort it out.
These machines are made for Miele by Liebherr. I had one of these give a lot of this problem F4, model was (8462). When the machine defrosts the seal on the NTC lets in moisture which gives a fault reading. I had one machine that i replaced several components but a month or so down the line it arose again. I disconnected buzzer for customer & on advice of Miele technical sealed NTC probes with silicone. Not heard anything back since.