Murphy’s law: The heater fails when it’s the coldest. That happened to me a few weeks ago, and a few days ago my workshop was able to read out the error codes: – Error code 664: Fuel supply display faulty – Error code 1412: Fire plug with flame monitoring Q8 – Error code 2251: Device locked I assume the last error code is normal, since in case of a defect the heater is deactivated. Therefore, only the first two – someone has an idea, what exactly could be defective? My current plan is to have the heating installed and to send it via my workshop to the special company Compramas (Compramas), which were already recommended here in another thread. I have already sent them a message with the above-mentioned error codes. If someone has an idea about this – thank you already in advance! Alpina_B3_Lux P.S. In addition, the Phaeton also displayed the error code 1274: Sturdy valve actuator incorrectly, but obviously not directly related to the heater, but to the heating / climate as a whole. Does anyone know exactly what is behind it?